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Cisco H.323 Signaling Interface User Guide, Release 4.3
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Cisco H.323 Signaling Interface
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Installing and Configuring Cisco HSI Software
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Provisioning the Cisco HSI
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Managing the Cisco HSI
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Troubleshooting Cisco HSI Alarms
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Cisco HSI Backup and Restore Procedures
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MML User Interface and Command Reference
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Skeleton Configuration File
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Example of an HSI Configuration File
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E-ISUP Name-to-Cause Value Lookup
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E-ISUP Cause-to-Name Value Lookup
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H.323 Name-to-Cause Value Lookup
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H.323 Cause-to-Name Value Lookup
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Table Of Contents
Restarting the HSI in a Live Network
HSI Configuration File Maintenance
Introduction to MML Command Operation for HSI
Initiating an MML Session to Enable DTMF on the HSI
Reverting to the Base Configuration
Quick Reference for Important Parameters
Configuring T.38 Fax on the Cisco PSTN Gateway
Configuring T.38 Fax on a Cisco IOS H.323 Gateway
Configuring T.38 Fax on a Cisco IOS MGCP Gateway
H.225 Information Message Support
Enabling Dynamic Packetization
Configuring Clear Channel on the Cisco HSI
Configuring G.726 on the Cisco HSI
Configuring G.729 Annex and G.729 Annex B
Using the Cisco HSI without a Gatekeeper (Non-RAS Mode)
Enabling the NON-RAS Mode of Operation on the Cisco HSI
Disabling the Non-RAS Mode of Operation on the Cisco HSI
H.323 Annex M.1 Support for Enhanced Interworking
Enabling Outbound H.323 Annex M.1 Support
Enabling Inbound H.323 Annex M.1 Support
Advertising H.323 Annex M.1 Support
Additional H.323 Annex M.1 Parameters
Configuring the Alternate Endpoints Feature
Per Call Support for the G.723.1 Codec
Provisioning the Cisco HSI
Revised: April, 2010, OL-11616-08
This chapter describes the data that must be provisioned for the Cisco H.323 Signaling Interface (HSI).
Cisco HSI Configuration
The Cisco HSI software provides an initial configuration file in /opt/GoldWing/currentPM/etc/GWmain.conf. (All configuration data is contained within configuration files.) The GWmain.conf file is created during the software installation and its contents are created when you enter values in response to prompts in the installation script.
If you issue the MML command prov-sta, the new configuration is stored in the directory /opt/GoldWing/currentPM/var/prov. This directory contains a link named active_config, which points to the currently active configuration. If you issue the MML command prov-rtrv:list, the command displays the contents of the directory in a column listing and marks the active configuration with an asterisk.
Note
If a configuration file name is longer than 9 characters, the asterisk does not appear in the column.
Typically, you use the following five MML commands to configure the Cisco HSI:
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HSI Configuration Data
There are three types of configuration data.
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Tip
Restarting the HSI in a Live Network
To change Restart data, first you must determine an acceptable off-peak time during which to change the configuration. The following steps show how to change a configuration while the HSI is operating in a live network.
Step 1
Step 2
Step 3
Step 4
Step 5
stp-callproc:timeout=600This command stops the HSI from accepting new calls; but, it sustains existing connected calls for a period of 600 seconds.
Step 6
Step 7
In response to the restart-softw command, the software displays the message:
GoldWing is starting.Then the software displays the message:
GoldWing has started.Step 8
HSI Configuration File Maintenance
As you modify a configuration during a provisioning session, the HSI software verifies that parameters are provisioned within allowable ranges. The software generates a checksum of the configuration file and writes the checksum as opt/GoldWing/currentPM/var/prov/configname/checksum.dat.
When the Cisco HSI starts, it attempts to read the active configuration, ensures that the configuration has been verified, and confirms that the checksum matches. If the active configuration is not verified or if the checksum is faulty, the HSI software reverts to using the configuration file opt/GoldWing/currentPM/etc/GWmain.conf.
All configuration data that can exist in the system is defined in the Skeleton Configuration file (see Appendix B, "Skeleton Configuration File." The Skeleton Configuration file (/opt/GoldWing/currentPM/etc/H323SkeletonFileSimple.dat) defines the data names and types (strings or numbers), and defines whether the data is modifiable or permanent. You can view this file; but, you should never modify it. Furthermore, you should not modify any configuration file directly. You should create configurations only by using the MML command line interface.
MML Configuration Commands
There are three types of MML configuration command:
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For more information about MML configuration commands, see Appendix A, "MML User Interface and Command Reference."
Note
The configuration export command is prov-exp, which exports the currently provisioned configuration of the Cisco HSI to a file.
Introduction to MML Command Operation for HSI
After the HSI software is installed, you can configure additional features. The following MML command examples show how to enable DTMF capability on the HSI. (For a description of the sys_config_static entry and the DTMF parameters, please see the section (HSI Data Categories).
Initiating an MML Session to Enable DTMF on the HSI
The following MML command example shows how to start an MML session and enable DTMF support of the HSI:
Step 1
/etc/init.d/CiscoGW startStep 2
mml
Step 3
prov-sta:srcver=active, dstver=myconf
Note
prov-add:name=sys_config_static, dtmfsupportedtype=dtmfprov-add:name=sys_config_static, dtmfsupporteddirection=bothprov-cpyrestart-softw
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Caution
Verifying the Configuration
The following MML command examples show how to verify that configuration changes have been correctly processed:
Step 1
prov-rtrv:list
Note
If configuration file names are longer than 9 characters, you can query for the currently active configuration file name by listing the contents of the /opt/GoldWing/currentPM/var/prov directory to examine the "active_config" link.Step 2
rtrv-configTo display a subset of the configuration, you can issue a command such as the following:
rtrv-config:sys_config_staticStep 3
quit
Reverting to the Base Configuration
The following MML command examples show how to revert to the base HSI configuration:
Step 1
mmlStep 2
restart-softw:init
Note
To return to the configuration "myconf," one would issue the command restart-softw:myconf.The following sections describe the SYS_CONFIG_STATIC, SYS_CONFIG_DYNAMIC, H323_SYS, Q931, RAS, H245 and CCPackage parameters in detail. The section "Quick Reference for Important Parameters" collects the most useful parameters into a single location for easy reference.
HSI Data Categories
The Cisco HSI data is divided into categories. The main categories are:
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The category names and names of configurable parameters are not case-sensitive; they also can be typed in lower-case. The individual parameters in these categories are all described in detail in the next section. The section "Quick Reference for Important Parameters" describes the most commonly modified values.
The section "HSI Feature Configuration" describes the configuration tasks required to enable specific features.
SYS_CONFIG_STATIC Parameters
Static data can be activated only at startup.
In the following example, the prov-add command adds the static parameter VSCA_PORT_NUMBER1 to a static configuration file. The prov-ed command modifies the value of the VSCA_PORT_NUMBER1 parameter. The prov-dlt command deletes the VSCA_PORT_NUMBER1 parameter from the static configuration file.
Example
prov-add:name=sys_config_static,vsca_port_number1=8003prov-ed:name=sys_config_static,vsca_port_number1=8002prov-dlt:name=sys_config_static,vsca_port_number1The parameters in Table 3-3 are written to a static configuration file or to a section within a file.
Table 3-3 SYS_CONFIG_STATIC Parameters
HOST_PORT_NUMBER1
[0-65535]
The first port number used by the Cisco HSI. The default value is 0.
Note
HOST_PORT_NUMBER2
[0-65535]
The second port number used by the Cisco HSI. The default value is 0.
Note
HOST_IPADDR1
STRING
The primary IP address of HSI.
HOST_IPADDR2
STRING
The secondary IP address of HSI.
Note
VSCA_IPADDR1
STRING
The primary IP address of the primary PGW 2200.
VSCA_IPADDR2
STRING
The secondary IP address of the primary PGW 2200.
Note
VSCB_IPADDR1
STRING
The primary IP address of the secondary PGW 2200.
Note
VSCB_IPADDR2
STRING
The secondary IP address of the secondary PGW 2200.
Note
VSCA_PORT_NUMBER1
[0-65535]
The first port number of the primary PGW 2200.
VSCA_PORT_NUMBER2
[0-65535]
The second port number of the primary PGW 2200.
Note
VSCB_PORT_NUMBER1
[0-65535]
The first port number of the secondary PGW 2200.
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VSCB_PORT_NUMBER2
[0-65535]
The second port number of the secondary PGW 2200.
Note
ClipClirSupported
STRING
CLI presentation or restriction is enabled if this parameter is present and set to anything other than "". For example, to enable CLIP/CLIR support, set this parameter explicitly to "Enabled."
Note
RaiSupported
STRING
RAI support is enabled if this parameter is present and set to anything other than "". For example, to enable RAI support, set this parameter to "Enabled."
DtmfSupportedDirection
STRING
This is set to "both", "tx," or "rx". If this parameter is not present or is set to any value other than "both," "tx," or "rx," the DTMF Relay feature is disabled.
DtmfSupportedType
STRING
This is set to "dtmf" or "basicString." If this parameter is not present or set to any other value, the DTMF Relay feature is disabled.
H225PavoSupported
STRING
Pavo support is enabled if this parameter is present and set to anything other than "". For example, set it to "Enabled."
PavoRedirScreeningInd
[0-3]
The value of the Pavo redirecting number screening indicator. (If this parameter is not provisioned, the default is Q.931 zero—user provided, not screened.)
PavoRedirReason
[0-15]
The value of the Pavo redirecting number reason field. This parameter has no default. If this parameter is not provisioned, the redirecting number parameter does not contain the Reason for Redirection field (octet 3b).
PavoRedirPresInd
[0-3]
The value of the Pavo redirecting number presentation indicator. (If this parameter is not provisioned, the default is Q.931 zero—no indication.)
CliInDisplaySupported
STRING
If this parameter is present and set to anything other than "", the Calling Number is also sent in the DISPLAY IE. The NetMeeting endpoint retrieves the calling party number from the DISPLAY IE in the H.225 Setup message. To enable this parameter, set it to "Enabled."
T38MaxVal
STRING
The T38MaxVal parameter has the following optional attributes that can be assigned values in a specific range.
Note
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T38Options
STRING
This T.38 Fax parameter is assigned one of the following optional values:
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T38Disabled
STRING
If this parameter is present and set to any text value other than "" (blank), the Cisco HSI disables T38 support. To re-enable fax support, the parameter must be deleted or set to blank ("").
AsymmetricHandlingSupported
STRING
Asymmetric Codec Treatment support is enabled if this parameter is present and set to anything other than "". To enable Asymmetric Codec Treatment, set this parameter to "Enabled."
UseConfID
STRING
Use this parameter to specify the precedence of extracting the Global Call ID from the Conference ID or the GUID in the H.225 Setup message. The provisioning of this property to a value other than "" gives precedence to the Conference ID. For example, set it to "Enabled." To set the precedence to the GUID field, the crafts person can either delete the property from the config or set it to "".
DualCLISupported
STRING
To enable Dual CLI support (see H.246 Annex C), set this parameter to anything other than "". For example, to explicitly enable Dual CLI support, set this parameter to "Enabled."
InjectPI8
STRING
Some PSTN networks do not notify the PGW/HSI that inband information is available. Typically, such information would be included in the ISUP ACM message, in the Optional Backward Call Indicator (OBCI) parameter.
For networks that do not supply the OBCI parameter in ACM messages, it is possible to configure the HSI to insert a progress indicator (PI) value 8 (indicating inband information is available) into the H.225 alerting message automatically. To do so, set the InjectPI8 parameter to a text value (for example, "enabled" or "true"). If the incoming ACM message does contain an OBCI, the InjectPI8 parameter has no effect. This parameter should be configured only if required, because it might be undesirable to insert PI8 automatically when no OBCI is present.
In HSI Release 4.3(2) and later, the behavior of the InjectPI8 parameter has been extended. If it is set to the specific text value of "NoOptBCI" (case-sensitive), in additional to the above behavior, the HSI also inserts PI8 into the alerting message for cases in which the incoming ISUP CPG (call progress) message does not contain an OBCI parameter either.
If the InjectPI8 parameter is set to the specific text value of "NoInBand" (case-sensitive), the HSI (in addition to the original behavior referred to earlier), inserts PI8 into the alerting message for the case in which the CPG message contains an OBCI parameter and the PSTN network has set the inband information indicator to the value 0 (no indication).
If the InjectPI8 parameter is set to the specific text value of "NoOptBCIorNoInBand" (case-sensitive), (again in addition to the original behavior), the HSI inserts PI8 into the alerting message for cases in which the CPG message contains no OBCI, or in which the OBCI has the inband information indicator set to 0.
InformationMsgDisabled
STRING
The H.225 information message conveys ringing tone information. Support for this can be disabled by setting this parameter to any text value. To re-enable the H.225 information message support, delete the parameter or set it to blank ("").
GRQMsgEnabled
STRING
The HSI can be configured to broadcast a gatekeeperRequest message if the gatekeeper returns a gatekeeperReject message. In most circumstances, Cisco recommends not enabling this support, to prevent the HSI from registering to undesirable gatekeepers in the network. If the broadcast must be enabled, to do so, set this parameter to any text value (for example, "enabled" or "true"). To return to the default behavior, delete the parameter or set it to blank ("").
NotifyMsgEnabled
STRING
The H.225 notify message conveys connected name and connected number information. To enable support for this message, set this parameter to any text value (for example, "enabled" or "true"). To disable support, delete the parameter or set it to blank ("").
CarrierCodeMapping
STRING
For some H.323 networks, the H.323 gatekeeper might have the capability to route calls depending on the destination circuit ID "group" field in the H.225 admissionRequest message. You can enable the Cisco HSI to interpret a "magic number" in the Cisco PGW dial plan as a command to insert such an ID into the admissionRequest message, for PSTN to H.323 calls. This is described in detail in the "Carrier Code Mapping" section. To enable the feature, set the parameter to any text value (for example, "enabled" or "true"). To disable the parameter, delete it or set it to blank ("").
Q931RedirSupported
STRING
H.225 Setup messages can contain a Q.931 redirecting number parameter. To enable support of this parameter, set the Q931RedirSupported parameter to any text value (for example, "enabled" or "true"). To disable support, delete the parameter or set it to blank ("").
Note
UseIncomingGkDestInfo
STRING
If this parameter is set to any text value (for example, "enabled" or "true"), the Cisco HSI modifies the called-party number (for calls that originate in the H.323 network) depending on the value returned by the gatekeeper in the destinationInfo field in H.225 admissionConfirm messages.
UseG726StaticPayload
STATIC
If this parameter is set to any text value, the HSI uses the static RTP/AVP payload value "2" to represent G.726 32kbit/sec to the MGCP gateway in the session description protocol (SDP) content. If the parameter is deleted or set to an empty string (""), the default behavior occurs (dynamic payload value).
AltEpSupported
STATIC
If this parameter is set to any text value (for example, "enabled" or "true"), for calls terminating in the H.323 network, the Cisco HSI uses the alternateEndpoints field in admissionConfirm messages to attempt multiple H.323 endpoints/gateways in sequential order. To disable the feature, delete the parameter or set it to blank (""). (See the section "Alternate Endpoints" for additional information.)
AltEpUseAliasAddr
STATIC
This parameter can be set to any text value (for example, "enabled" or "true"). The AltEpSupported parameter must be present for this parameter to take effect. (See the section "Alternate Endpoints" for additional information.)
AltEpCauseAllowed
STATIC
This parameter can be set to a string of cause codes (for example, "38 42") or set to blank (""). The AltEpSupported parameter must be present for this parameter to take effect. (See the section "Alternate Endpoints" for additional information.)
AltEpCauseDisallowed
STATIC
This parameter can be set to a string of cause codes (for example, "38 42") or set to blank ("").The AltEpSupported parameter must be present for this parameter to take effect. (See the section "Alternate Endpoints" for additional information.)
OutgoingCallUnansweredRelWait
STRING
If set to any non-empty value, the HSI waits for the other side to release a call when the call is not answered.
UseSysTimeEnabled
STRING
If set to any non-empty value, the HSI uses system-time instead of UTC time in the platform.log
IpTOS
[0-184]
Valid values for IpTOS are 0, 32, 40, 64, 72, 96, 104, 128, 136, 184. If you specify any other value in the range 0-184, the HSI sets the value to the default 96.
ConnectedCallsMaxDuration
[0-100]
Enables an operator to set a maximum duration (in hours) for a connected call. If a call exceeds the maximum duration, the HSI removes it from the connected state. Default is 0, which represents an infinite duration.
1 PGW = Public Switched Telephone Network (PSTN) Gateway
SYS_CONFIG_DYNAMIC Parameters
Dynamic data can be activated during system run time.
To modify the SYS_CONFIG_DYNAMIC parameters in Table 3-4, use the sys_config_dynamic MML name variable for the prov-add, prov-dlt, and prov-ed commands. You need not halt and restart call processing for the changes to take effect.
In the following example, the prov-add command adds the dynamic parameter OVLDLEVEL1PERCENT to a dynamic configuration file. The prov-ed command modifies the value of the OVLDLEVEL1PERCENT parameter. The prov-dlt command deletes the OVLDLEVEL1PERCENT parameter from the dynamic configuration file.
Example
prov-add:name=sys_config_dynamic,OVLDLEVEL1PERCENT=20prov-ed:name=sys_config_dynamic,OVLDLEVEL1PERCENT=25prov-dlt:name=sys_config_dynamic,OVLDLEVEL1PERCENTThe MML commands write the parameters in Table 3-4 to a dynamic configuration file or to a section within a file.
H323_SYS Parameters
The parameters in Table 3-5 are required for Cisco HSI initialization. For normal conditions, you should not need to modify these parameters.
Caution
Note
Q931 Parameters
To modify the parameters listed in Table 3-6, use the q931 MML name variable for the prov-add, prov-dlt, and prov-ed commands.
In the following example, the prov-add command sets the Q.931 parameter responseTimeOut to the value 5.
Example
prov-add:name=q931,responseTimeOut=5If you modify any of the Q931 parameters, you must restart the HSI to enable them to take effect.
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RAS Parameters
The parameters in Table 3-7 are required for RAS stack initialization. To modify the RAS parameters, use the ras MML name variable for the prov-add, prov-dlt, and prov-ed commands.
In the following example, the prov-add command sets the RAS parameter maxfail to the value 3.
Example
prov-add:name=ras,maxfail=3The array index [i] in some of the parameter names in the first column of Table 3-7 must be replaced with a valid braced index from 1 to 20, and must be continuous and unique (that is, it must contain no duplicates).
The Update Type column in Table 3-7 shows when the change to a parameter takes effect after it is modified:
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H.245 Parameters
To modify the H.245 parameters listed in Table 3-8, use the h245 MML name variable for the prov-add, prov-dlt, and prov-ed commands.
In the following example, the prov-add command sets the H.245 parameter masterSlave.timeout to the value 5.
Example
prov-add:name=h245,masterSlave.timeout=5The Update Type column in Table 3-8 shows when a change to an H.245 parameter takes effect after it is modified:
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Table 3-9, Table 3-10, and Table 3-11 list the parameters and modes related to the configuring of codecs. The array index [i] must be replaced with a valid braced index from 1 to 20. The braced index must be continuous and unique (that is, there must be no duplicates).
Codec Selection
The Cisco HSI negotiates the media stream codec to establish a match between the PSTN MGCP media gateway (for example, the Cisco AS5xxx series or Cisco MGX series) and the H.323 endpoint or H.323 gateway. To match codecs, the MGCP gateway must be configured to match what is expected at the H.323 end. Similarly, the Cisco HSI also must be configured with the same codecs.
The Cisco HSI receives a list of codecs from the MGCP gateway and tries to match them to the codecs that are configured on the HSI. The HSI advertises all of the successful matches in the H.245 terminalCapabilitySet messaging with the H.323 endpoint.
In order to achieve a successful match, the HSI seeks to find common codec technologies (for example, G.711, G.729, etc) between the PSTN side and the H.323 network, and also common media payload packet sizes. The codecs that are to be supported are configured under the H245.caps, H.245.chan and H.245.modes parameters. These parameters reflect the structures used in the H.245 specification to describe media capabilities. Typically, each codec requires six configuration entries, although some codecs are slightly different (for example, G.723.1). The six basic entries are:
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In the preceding entries, xxx is the codec name keyword, which can be:
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The value given to the caps[i].audio.xxx and chan[i].audio.xxx parameters is known as the "frames per packet" (fpp) value, which is a way of representing the packet size for a given codec technology (a frame is the smallest discrete quantity of bytes that can be encoded/decoded for that particular codec). Table 3-12 illustrates the relationship between packet size, packetization period (that is, audio duration) and byte size of the payload, for some popular codecs and common packetization periods. Notice that G.711 does not have a concept of frames per packet because there is no encoding into frames, but a value of eight 8-bit samples (or bytes) per frame is the convention.
Table 3-12 HSI Codec Matrix
G.711A/u-law
10
10
80
20
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160
G.729/a/b
2
20
20
3
30
30
G.723.1
1
30
24
2
60
48
The configuration for G.726 and G.clear is described in detail in the "Configuring G.726 on the Cisco HSI" section.
Sample Codec Configuration
The following example shows the series of MML commands required to configure the codec G723.1:
Example
mml>prov-add:name=h245, caps.table[x].entryNo = 7231prov-add:name=h245, caps.table[x].audio.g7231.maxAudioFrames = 12prov-add:name=h245, caps.table[x].audio.g7231.silencesuppression = 1prov-add:name=h245, chan[x].name = g7231prov-add:name=h245, chan[x].audio.g7231.maxAudioFrames = 12prov-add:name=h245, chan[x].audio.g7231.silencesuppression = 1prov-add:name=h245, modes[x].audio.g7231prov-add:name=h245, modes[x].name = g7231It is important to determine and configure the fpp value correctly on the Cisco HSI per codec. If the value is incorrect, the codec may not be negotiated successfully between the HSI and the H.323 endpoint. It is also important to configure the MGCP gateway correctly. The gateway should be configured to provide static payload values for the required codecs, rather than dynamic payload types (see Table 4 in RFC 3551, Schulzrinne and Casner), although the Cisco HSI does support dynamic payload values for the particular codecs that require it.
CCPackage Parameters
The Cisco HSI uses the CCPackage configuration to map values for PSTN/H.323 message content. The majority of the CCPackage parameters are permanent data for internal HSI use, and are not modifiable. The parameters that are modifiable are recorded in the "Quick Reference for Important Parameters" section.
Quick Reference for Important Parameters
Table 3-13, Table 3-14, Table 3-15, and Table 3-16 can be used in initial HSI configuration. The tables present parameters that you might use frequently to align the Cisco HSI with an existing PSTN or Voice over IP network.
Table 3-13 presents important CCPackage parameters.
The following MML command example shows the command sequence used to provision the CCPackage parameters provided in the preceding table.
Example
mmlprov-sta::srcver=active, dstver=myconfprov-ed:name=CCPackage, A_CC_ANumDataSI=2prov-cpyrestart-softwTable 3-14 presents important SYS_CONFIG_STATIC parameters.
Table 3-14 SYS_CONFIG_STATIC Parameters
CarrierCodeMapping
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Allows the mapping of a special tech prefix (the format of which is CCxCy) to the DestinationCircuitID "group" field in the ARQ message. This feature works only with IOS Gatekeeper build Release 12.2(15)T10 or later. See the section "Carrier Code Mapping" for more information.
ClipClirSupported
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Allows transit of CLI presentation/screening information.
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DtmfSupportedType
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Selects the DTMF type during H.245 terminal capabilities exchange.
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DtmfSupportedDirection
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Selects DTMF transit direction.
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H225PavoSupported
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Allows transit of redirecting number parameter (contained in Cisco CallManager H.225 Setup messages—nonStandardControl field).
RaiSupported
For example:
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Allows H.225 RAS RAI messages to be sent to the gatekeeper if the EISUP link fails or if the HSI is under heavy load.
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NotifyMsgEnabled
For example:
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Allows transit of connected number, display information, and generic notification indicator in H.225 Notify messages.
VSCB_IPADDR1/2
IP address, for example: "10.10.10.1"
Allows IP address configuration of second PGW.
VSCB_PORT_NUMBER1/2
Port number, for example: 8003
Allows port configuration of second PGW.
The following MML command example shows the command sequence used to provision the SYS_CONFIG_STATIC parameters provided in the preceding table.
Example
mmlprov-sta::srcver=active, dstver=myconfprov-ed:name=SYS_CONFIG_STATIC, DtmfSupportedType="dtmf"rov-cpyrestart-softwTable 3-15 presents important RAS parameters.
Table 3-15 Important RAS Parameters
gateway.prefix[1]
gateway.prefix[2]
For example: 020
HSI prefix (for gatekeeper registration)
timeToLive
Integer (to specify number of seconds)
for example, 45Note
RAS registration time to live.
See Table 3-7.
The following MML command example shows the command sequence used to provision the RAS parameters provided in the preceding table.
Example
mmlprov-sta::srcver=active, dstver=myconfprov-ed:name=RAS, timeToLive=45prov-cpyrestart-softwTable 3-16 presents common H.245 parameters for enabling the G.729 codec.
The following MML command example shows the command sequence used to provision the H.245 parameters provided in the preceding table for enabling the G.729 codec. Provisioning the G.729 codec on the Cisco HSI supports passing SS7 calls to the Cisco CallManager through a gateway running the Media Gateway Control Protocol (MGCP).
Example
mml>prov-sta::srcver="active",dstver="g729"prov-add:name="H245",caps.table[4].audio.g729="2"prov-add:name="H245",caps.table[4].entryno="729"prov-add:name="H245",chan[4].audio.g729="2"prov-add:name="H245",chan[4].name="g729"prov-add:name="H245",modes[3].audio.g729=""prov-add:name="H245",modes[3].name="g729"
HSI Feature Configuration
This section describes how to enable the following HSI features:
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Asymmetric Codec Treatment
The Asymmetric Codec Treatment feature averts the potential for inconsistencies in codec selection, which can result if the open channel requests are sent by each endpoint at nearly the same time, so that neither side has received an open channel request prior to sending one. In practice, such asymmetric conditions occur only for slow start calls. When there is a fast start recipient, both channels agree to use the same codec in unison.
The Asymmetric Codec Treatment support is enabled if this parameter is present and set to anything other than "". For example, support is enabled if the parameter is explicitly set to "Enabled." To enable Asymmetric Codec Treatment, enter the following command:
prov-add:name=sys_config_static, asymmetrichandlingsupported = "Enabled"Empty Capability Set
The Empty Capability Set feature enables an H.323 endpoint to send a TCS message with empty capabilities during a call. The TCS message causes the audio channels to close. This action enables the negotiation and opening of new audio channels.
The Empty Capability Set feature is useful if the H.323 endpoint wishes to change the audio codec during a call or if the endpoint needs to divert the media streams to a different location. Typically, the feature is used to place a call on hold to disable the media stream until the user presses the Resume button.
The Empty Capability Set feature on the HSI requires no provisioning.
Note
H.323 Hairpin
The H.323 Hairpin feature can be used to connect a call between two H.323 endpoints without the use of resources on the media gateway. For example, the PGW can respond to the dialed number in an incoming H.323 call by routing the call to another HSI (perhaps the same HSI) rather than routing the call to the PSTN. In this case, the originating and terminating HSIs establish the call normally but pass the H.245 address of the H.323 endpoints. This enables the two endpoints to use H.245 to negotiate media channels with each other directly, independent of the HSI.
The H.323 Hairpin feature on the HSI requires no provisioning. However, to operate throughout the system, H.323 Hairpin must be enabled on the PGW. On the PGW, you enable H.323 Hairpin through a trunk group property by issuing the following commands:
prov-add:trnkgrpprop:name="2000",AllowH323Hairpin="1"prov-add:trnkgrpprop:name="3000",AllowH323Hairpin="1"
Note
Refer to Cisco PGW 2200 and Cisco IOS documentation at www.cisco.com for further information on these commands.
T.38 Fax
The T.38 Fax feature enables the HSI to alter a call, initially established for voice, to support a fax transmission.
When a fax call is initiated, a voice call is established. When the terminating gateway detects the fax tone generated by the terminating fax machine, the gateway initiates a T.38 mode request using H.245 procedures from the terminating gateway. If the opposite end of the call acknowledges the T.38 mode request, the initial audio channel is closed and a T.38 fax relay channel is opened.
You enable T.38 Fax for the HSI by specifying static system data parameters. By default, T.38 is provisioned on the HSI by use of the following commands:
prov-add:name=sys_config_static,t38maxval="MaxBit 0x90, FxMaxBuf 0xc8, FxMaxData 0x48"prov-add:name=sys_config_static,t38options="FxFillBit 0, FxTransMMR 0, FxTransJBIG 0, FxRate Trans, FxUdpEC Red"Table 3-3 describes the T.38 static system parameters. The T.38 parameters for HSI correspond to T.38 parameters proposed in the ITU T.38 recommendation.
Configuring T.38 Fax on the Cisco PSTN Gateway
To enable T.38 Fax throughout the system, you must enable T.38 Fax on the Cisco PGW. On the PGW, T.38 is enabled through a trunk group property by use of the following MML command:
prov-add:trnkgrpprop:name="2000",FaxSupport="1"Configuring T.38 Fax on a Cisco IOS H.323 Gateway
Enable T.38 Fax on a Cisco IOS H.323 gateway by issuing the following IOS commands:
voice service voipfax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback noneConfiguring T.38 Fax on a Cisco IOS MGCP Gateway
Enable T.38 fax on a Cisco IOS MGCP gateway by issuing the following IOS commands:
voice service voipfax protocol t38 ls-redundancy 0 hs-redundancy 0 fallback nonemgcp package-capability fxr-packageRefer to Cisco PGW 2200 and Cisco IOS documentation at www.cisco.com for further information on these commands.
H.225 Information Message Support
Cisco CallManager uses the H.225 Information message (ringback tone) during transfer to indicate that ringback tone is on or off. The Cisco HSI now supports this message to correctly interoperate with Cisco CallManager.
Support for the H.225 Information message is enabled by default. A craftsperson can disable H.255 Information message support through a new property called Information MsgDisabled by issuing the following MML command:
prov-add:name=sys_config_static,informationmsgdisabled = "True"HSI Support for Tech Prefixes
The Cisco HSI now maps the "*" (asterisk, or star) and "#" (number sign, or hash) H.225 prefixes to the PGW for H.323 to PSTN calls as follows:
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The craftsperson can change these values by issuing the following MML command:
prov-ed:name=ccpackage,hash='C'Cisco HSI now maps the EISUP "B" to "*" and "C" to "#" (Called Party Number) for PSTN to H.323 calls.
H.323/SIP Interworking
H.323 to SIP and SIP to H.323 interworking supports calls between SIP and H.323 based networks, which are connected through the Cisco PGW 2200's SIP interface. Support for SIP was introduced in the Cisco PGW 9.6 release. No additional HSI configuration is needed to support this feature.
In addition, the HSI supports advanced SIP call flows (including call transfer and call divert) through the use of Annex M.1 functionality, when interworking with H.323 endpoints/gateways that support this, such as Cisco Call Manager. This additional functionality is only available with the Cisco PGW 9.7 release.
HSI Notify Message Support
Cisco Call Manager uses H.225 Notify messages during call transfer to indicate the transferees name and number information to the calling party. That is, when A calls B, and B transfers the call to C, the information about C is sent to A by means of the H.225 Notify message.
The HSI supports this message to correctly interoperate with Cisco Call Manager.
To enable this functionality, enter the following commands in an MML provisioning session:
prov-add:name=sys_config_static, NotifyMsgEnabled=enabledprov-cpyrestart-softwFor this functionality to be disabled, the NotifyMsgEnabled parameter entry must be deleted or set to "", as shown in the following example:
prov-ed:name=sys_config_static, NotifyMsgEnabled=""prov-cpyrestart-softwAdjustable Packetization
The Cisco HSI enables adjusting the payload size while opening media channels. The HSI can reduce the packetization from its advertised value to the value advertised by the remote endpoint. Rather than reject calls, the HSI reduces payload size from what is configured in the HSI to what is proposed by the Terminal Capability Set (TCS) exchange. This is useful when interworking with endpoints that operate at different packetization sizes from the HSI configuration. It may not be desirable always to enable this feature (for example, if it is preferable for the VoIP network to maintain a consistent packet size, or if some endpoints/MGCP gateways cannot cope with receiving RTP payload sizes different from the payload size for which they are configured).
Note
Adjustable packetization enables the HSI to negotiate a packetization period that might differ from that provisioned on the Media Gateway. The codec packetization is asymmetric, which can cause problems with some endpoints.
Figure 3-1 illustrates how the HSI synchronizes the packetization value with a remote endpoint.
Figure 3-1 Synchronizing Packetization Values
Enabling Dynamic Packetization
The SYS_CONFIG_DYNAMIC parameter DynamicPacketizationSupported is used to enable this adjustable packetization feature.
To enable Dynamic Packetization Support, issue the following MML command:
prov-add:name=sys_config_dynamic, DynamicPacketizationSupported="enabled"To disable this feature, delete this parameter or set it to blank ("").
Carrier Code Mapping
Carrier Code Mapping enables routing based on a prefix or carrier identifier. When the HSI receives a called party number with the format CCxCy from the PGW 2200 (in which C is the single overdecadic digit C and x is the single- or multiple-digit carrier code and y is the single- or multiple-digit destination number), the HSI can advise the gatekeeper of the carrier code.
Figure 3-2 illustrates how carrier code mapping works. In this illustration, the call is to 0800123456, and the PGW determines that it is destined to be completed by the carrier numbered 999.
Figure 3-2 Carrier Code Mapping
The HSI inserts y into the e164 destinationInfo field of the ARQ message and into the H.225 Setup message; it inserts x into the DestinationCircuitID group field in the ARQ message.
The dial plan on the PGW 2200 must be configured to perform the appropriate digit modification to prepend the carrier ID to the called party number in the special CCxCy carrier-code format.
To configure the Cisco HSI to perform carrier code mapping, issue the following MML commands:
prov-add:name=sys_config_static, CarrierCodeMapping="enabled"restart-softw
Note
Configuring Clear Channel on the Cisco HSI
The Clear Channel capability (identified as G.Clear or gclear in this document) enables support for both voice and data calls on a network. However, the end applications are responsible for packet loss and error recovery. For more information, refer to the document G.Clear, GSMFR, and G.726 Codecs and Modem and Fax Passthrough for Cisco Universal Gateways at http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a00800b3568.html.
The Cisco HSI interoperates with Cisco voice gateways (for example, the Cisco AS54xx series or VISM), which advertise G.Clear capability via MGCP signaling using the following methods: G.Clear, G.nX64, CCD. The Cisco HSI automatically selects the correct method depending on the gateway that originates or terminates the call.
Table 3-17 presents examples of configuration commands that may be required to implement a particular G.Clear configuration.
Configuring G.726 on the Cisco HSI
The G.726 codec enables transcoding a PCM channel to or from an ADPCM data stream. The standard supports four data rates:16, 24, 32 and 40 kbit/sec.
G.726 capability is advertised by the Cisco HSI and other H.323 gateways/endpoints in H.225 fast-start elements, in H.245 (tunneled or a separate TCP/IP connection) terminal capability (TCS) messages, and open logical channel (OLC) messages.
Currently, H.323 devices use several different methods to advertise G.726. ITU G.726 Annex B defines one method, referred to in this document as g726-generic. Cisco H.323 gateways (for example, the Cisco AS5400) support an alternate method referred to as g726-cisco. There is another method used by the OpenH323 project; however, the Cisco HSI does not support that method.
MGCP gateways advertise G.726 capability using the method described in RFC 3551 (RTP Profile for Audio and Video Conferences with Minimal Control). The four data rates use dynamic payloads; however, the 32kbit/sec data rate, alternatively, can have a static payload value of 2 (this alternative value is being phased out).
You can configure the Cisco HSI for 32kbit/sec MGCP support using dynamic or static payload values. In addition, you can configure the Cisco HSI to support g726-generic and/or g726-cisco for the H.323 signaling. If possible, it is best to select g726-cisco for your network because it offers additional flexibility.
The g726-generic method cannot indicate the data rate in H.245 TCS messages. The ITU standard specifies that the data rate is only advertised in the OLC messages.
Note
The fact that the g726-generic method cannot indicate the data rate in an H.245 TCS message is not a problem if the MGCP gateway and your network are designed to support all data rates for this codec. However, if all data rates are not supported, it is possible for the remote endpoint/gateway to select a non-preferred or non-supported data rate in the OLC message.
Note
If a data-rate preference list specifies only a single rate (for example, G.726-16kbit/sec), it is not possible to advertise this fact in the TCS message. Subsequently, the remote endpoint may attempt to open the media stream using an unsupported data rate (perhaps, G.726-24kbit/sec).Whenever OLC messages are exchanged and a non-supported G.726 data rate is detected, to prevent unnecessary call clearing, the Cisco HSI always attempts to send the data rate selection to the MGCP gateway. If the MGCP gateway does not support the selected data rate, it sends a message to the Cisco PGW to clear the call.
If a non-preferred G.726 data rate is selected over a higher-preference codec, the HSI continues with the call using the non-preferred data rate. This is preferable to the alternative (aborting the media stream, invoking an empty capability exchange followed by a re-negotiation of codecs and new OLC messaging). The alternative causes call processing delay and overhead associated with switching media streams.
Note
Refer to the Cisco H.323 Signaling Interface User Guide for information about Cisco HSI MML commands.
Table 3-18 presents examples of configuration commands that may be required to implement a particular G.726 configuration.
Configuring G.729 Annex and G.729 Annex B
Table 3-18 presents examples of configuration commands that may be required to implement a particular configuration of G.729 Annex A or G.729 Annex B.
Using the Cisco HSI without a Gatekeeper (Non-RAS Mode)
The Non-RAS mode feature (using the HSI without a gatekeeper) of the Cisco Media Gateway Controller (MGC) software running on the Cisco PSTN Gateway (PGW) 2200 and Cisco H.323 Signaling Interface (HSI) enables service providers to create a simplified network without a gatekeeper, for networks that do not require gatekeeper features such as security.
In Non-RAS mode, the Cisco PGW 2200 converts called numbers into one or more IP addresses in the dial plan to support load sharing over multiple HSIs. This mechanism supports H.323 endpoints that have multiple IP addresses. With such support, when an initial IP address does not work, subsequent attempts are made to the alternative IP addresses for the same endpoint.
If the Cisco PGW 2200 sends an IP address to the HSI over EISUP, the HSI sends a H.225 Setup message directly to the endpoint. In addition, the Cisco PGW 2200 stores the H.323 Destination IP address in the Cisco PGW 2200's Call Detail Record (CDR).
Non-RAS mode enables deployment of a Cisco PGW 2200 with a connected Cisco HSI without a gatekeeper in networks that do not require admission, location of the H.323 endpoint, or when selection of the endpoint does not benefit from H.323 mechanisms such as Resource Availability Indication (RAI).
To enable the Non-RAS mode of operation on the Cisco HSI, the feature must also be enabled on the Cisco PGW 2200. Non-RAS Mode is supported by the Cisco PGW 2200 Release 9.7.
Note
Enabling the NON-RAS Mode of Operation on the Cisco HSI
To enable Non-RAS mode on the Cisco HSI, enter the following MML command:
prov-add:name=RAS, manualRASDisabling the Non-RAS Mode of Operation on the Cisco HSI
To disable Non-RAS mode, enter the following MML command:
prov-dlt:name=RAS, manualRASH.323 Annex M.1 Support for Enhanced Interworking
The H.323 Annex M.1 support allows for enhanced service interoperability with H.323 networks which support this protocol, PBX protocols, and PSTN protocols or SIP.
To process Annex M.1 message content, the HSI maps the Annex M.1 message into an equivalent tunneled message within EISUP, which it delivers to the PGW 2200. You must provision this capability in the HSI for each direction (inbound and outbound). Support for Annex M.1 is advertised in the RRQ (registration request) and ARQ (admission request) to the gatekeeper, if configured.
Enabling Outbound H.323 Annex M.1 Support
To enable outbound QSIG tunneling, issue the following MML command:
mml>prov-add:name=sys_config_dynamic, EnableOutboundAnnexM1 ="enabled"Enabling Inbound H.323 Annex M.1 Support
To enable reception of inbound tunneled QSIG, issue the following MML command:
mml>prov-add:name=sys_config_dynamic, EnableInboundAnnexM1 ="enabled"Advertising H.323 Annex M.1 Support
To advertise Annex M.1 support to a gatekeeper, issue the following MML command:
mml>prov-add: name=sys_config_dynamic, IncludeAnnexM1inRRQ="enabled"Additional H.323 Annex M.1 Parameters
To advertise Annex M.1 functionality in H.225 registrationRequest messages in the supportedTunnelledProtocols field, issue the following command in a provisioning session:
mml>prov-add: name=sys_config_dynamic, IncludeAnnexM1inRRQ="enabled"To advertise Annex M.1 functionality in H.225 admissionRequest messages in the desiredTunnelledProtocol field, issue the following command in a provisioning session:
mml>prov-add: name=sys_config_dynamic, IncludeAnnexM1inARQ="enabled"To transport Annex M.1 content in H.225 facility messages during overlap call establishment, issue the following command in a provisioning session:
mml>prov-add: name=sys_config_dynamic, SendAnnexM1inOverlapFacility="enabled"If this parameter is not configured, the default action is to transport the Annex M.1 content during overlap call establishment in H.225 Information messages.
Alternate Endpoints
The Alternate Endpoints feature enables the Cisco HSI, connected to a Cisco PGW 2200, to support call routing in response to alternateEndpoint fields in RAS admissionConfirm messages sent from an H.323 gatekeeper. The support of Alternate Endpoints enables the PGW 2200 to attempt to route a call to an alternative endpoint when connection to an initial endpoint fails. The PGW 2200 attempts to connect to alternate endpoints through a sequence of endpoints according to an established priority order. Support of alternate endpoints is important for Wholesale VoIP carriers, which have several choices for routing calls based on criteria such as voice quality or least cost.
Note
A gateway operating the H.323 protocol determines the need to use an H.323 alternate endpoint when one of the following circumstances occurs:
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Note
To support Alternate Endpoints the Cisco HSI operates according to the following requirements:
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Configuring the Alternate Endpoints Feature
To enable the Alternate Endpoints feature on the Cisco HSI, the following parameters are available:
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Configuring AltEpSupported
If the AltEpSupported parameter is set to any text value (for example, "enabled" or "true"), the HSI enables the Alternate Endpoints feature.
If this parameter is set to any text value (for example, "enabled" or "true"), the HSI enables the functionality.
If the parameter is deleted or set to blank (""), the feature is disabled.
Example:
prov-add:name=sys_config_static, AltEpSupported="enabled"Configuring AltEpUseAliasAddr
If the AltEpUseAliasAddr parameter is set to any text value (for example, "enabled" or "true"), the HSI uses the aliasAddress value in the alternateEndpoints field (from the gatekeeper registrationConfirm message), and modifies the called-party number and destinationAddress in the outgoing setup message accordingly.
The parameter AltEpUseAliasAddr is a static system parameter that is configured in the HSI configuration file GWmain.conf.
If this parameter is set to any text value (for example, "enabled" or "true"), the HSI uses the aliasAddress value in the alternateEndpoints field, and modifies the called-party number and destinationAddress in the outgoing Setup message.
If the parameter is deleted or set to blank (""), the HSI does not modify the called party number and destinationAddress.
Example:
prov-add:name=sys_config_static, AltEpUseAliasAddr="enabled"Configuring AltEpCauseAllowed or AltEpCauseDisallowed
The parameters AltEpCauseAllowed and AltEpCauseDisallowed are static system parameters that are configured in the HSI configuration file GWmain.conf.
These parameters enable defining the cause codes that invoke or do not invoke the alternate endpoints feature behavior. Only one of these two parameters should be configured.
These parameters are configured as a string of cause codes. By default, these parameters are absent or set to zero. You can set these parameter to any value in the Q.850 specification (range [1-127]).
If the HSI receives a releaseComplete message with no Q.850 cause code (the Q.850 cause code is optional in H.323 releaseComplete messages), the HSI does not attempt any alternate endpoint that was present in the admissionConfirm (ACF) message. The HSI releases the call.
The HSI never attempts alternate endpoints if it receives cause codes 16=Normal call clearing or 17=User busy.
Example 1:
The following example command determines that the HSI attempts alternate endpoints only in response to cause code 38=Network out of order or 42=Switching equipment congestion. The HSI releases the call for all other cause codes.
Prov-add:name=sys_config_static, AltEpCauseAllowed="38 42"Example 2:
The following example command determines that the HSI attempts alternate endpoints for all cause codes except 1=Unallocated number (and cause codes 16, and 17, which are hard-coded internally within the HSI).
Prov-add:name=sys_config_static, AltEpCauseDisallowed="1"Per Call Support for the G.723.1 Codec
For releases of the Cisco HSI prior to HSI 4.3 Patch 5, the silence suppression field of the G.723.1 codec was provisioned for all calls, which could cause problems for some IP-IP gateways because IP-IP gateways check the suppression parameter strictly for every call.
HSI 4.3 Patch 5 enabled the HSI to support dynamic G.723.1 codecs on a per-call basis. For the Session Description Protocol (SDP), the HSI supports the following G.723.1 dynamic payload values:
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In the preceding list, the HSI processes the codecs G.723.1-H/8000 and G.723.1-L/8000 as G.723.1 without silence suppression. The HSI processes codecs G.723.1a-H/8000 and G.723.1a-L/8000 as G.723.1 with silence suppression enabled.
If your HSI configuration has 6 codecs configured before you attempt to enable this enhancement, start the enumeration of the payload types for the new codecs with the value 7, as shown in the following example:
* SYS_CONFIG_STATIC.G7231DynCodecSupported = enabled
* SYS_CONFIG_DYNAMIC.UsePayloadTypeMapping = true
* h245.caps.table[7].audio.g7231-dyn.maxAudioFrames = 1
* h245.caps.table[7].audio.g7231-dyn.silencesuppression = 0
* h245.caps.table[7].entryNo = 72311
* h245.caps.table[8].audio.g7231a-dyn.maxAudioFrames = 1
* h245.caps.table[8].audio.g7231a-dyn.silencesuppression = 1
* h245.caps.table[8].entryNo = 72312
* h245.chan[7].audio.g7231-dyn.maxAudioFrames = 1
* h245.chan[7].audio.g7231-dyn.silencesuppression = 0
* h245.chan[7].name = g7231-dyn
* h245.chan[8].audio.g7231a-dyn.maxAudioFrames = 1
* h245.chan[8].audio.g7231a-dyn.silencesuppression = 1
* h245.chan[8].name = g7231a-dyn
* h245.modes[7].audio.g7231-dyn = NULL
* h245.modes[7].name = g7231-dyn
* h245.modes[8].audio.g7231a-dyn = NULL
* h245.modes[8].name = g7231a-dyn
Note
