Configuring Digital Voice Ports

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    voice-port slot / port:ds0-group-number

4.    shutdown

5.    exit

6.    controller {t1 | e1} slot/port

7.   Do one of the following:

8.    exit

9.    voice-card slot

10.    codec complexity {high | medium} [ecan-extended]

11.    exit

12.    Repeat Step 6, then continue with Step 13.

13.   Do one of the following:

14.    exit

15.    Repeat Step 3, then continue with Step 16.

16.    no shutdown

17.    end

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	voice-port slot / port:ds0-group-number Example: Router(config)# voice-port 1/0:23	Enters voice-port configuration mode on the selected slot, port, and DS0 group. Note    The syntax of this command is platform-specific. For the syntax for your platform, refer to the Cisco IOS Voice Command Reference. Note    For the Cisco 880 series platforms, the command syntax does not include a slot number, only the port is identified. If the primary voice interface is FXS and the backup is BRI, then ports 0, 1, 2, and 3 are analog voice ports, and ports 4 and 5 are digital. If the primary voice interface is BRI, then ports 1, 2, 3, and 4 are digital.
Step 4	shutdown Example: Router(config-voiceport)# shutdown	Shuts down all voice ports assigned to the T1 interface on the voice card.
Step 5	exit Example: Router(config-voiceport)# exit	Exits voice-port configuration mode.
Step 6	controller {t1 | e1} slot/port Example: Router(config)# controller t1 1/0	Enters controller configuration mode on the T1 controller on the selected slot and port.
Step 7	Do one of the following: no ds0-group ds0-group-number no pri-group timeslots timeslot-list Example: Router(config-controller)# no ds0-group 1 Example: Router(config-controller)# no pri-group timeslots 1,7,9	Removes the related DS0 groups. or Removes the related PRI group.
Step 8	exit Example: Router(config-controller) exit	Exits controller configuration mode and returns to global configuration mode.
Step 9	voice-card slot Example: Router(config)# voice-card 1	Enters voice-card configuration mode on the specified slot. slot--Slot number of the voice card. Range is 0 to 6, depending on platform.
Step 10	codec complexity {high | medium} [ecan-extended] Example: Router(voice-card)# codec complexity high ecan-extended Example:	Changes codec complexity or changes the echo canceller (EC) from the proprietary Cisco G.165 EC to the G.168 extended EC. high --Supports up to six voice or fax calls per DSP module (PVDM-12), using the codecs: G.723, G.728, G.729, G.729 Annex B, GSMEFR, GSMFR, fax relay, or any of the medium complexity codecs. medium --Supports up to 12 voice or fax calls per DSP module (PVDM-12), using the codecs: G.711, G.726, G.729 Annex A, G.729 Annex A with Annex B, and fax relay. Default value. ecan-extended --(Optional) Selects the G.168 extended echo canceller. For more information, see the "How to Configure the Extended G.168 Echo Canceller" section. Specifying the codec complexity restricts the codecs available in dial-peer configuration mode. All voice cards in a gateway must use the same codec complexity.
Step 11	exit Example: Router(voice-card) exit	Exits voice-card configuration mode and returns to global configuration mode.
Step 12	Repeat Step 6, then continue with Step 13.	--
Step 13	Do one of the following: ds0-group ds0-group-number timeslots timeslot - list type {e&m-immediate | e&m-delay | e&m-wink-start | fxs-ground-start | fxs-loop-start | fxo-ground-start | fxo-loop-start} pri-group timeslots timeslot - list Example: Router(config-controller)# ds0-group 0 timeslots 1-24 type e&m-wink-start Example: Router(config-controller)# pri-group timeslots 1,7,9	Defines the T1 or E1 channels for use by compressed voice calls and the signaling method that the router uses to connect to the PBX or CO. Note    If you are configuring PRI groups instead of DS0 groups, omit this step and proceed to Step 15. or Specifies an ISDN PRI on a channelized T1 or E1 controller. Note    When configuring PRI groups, you must also configure the isdn switch-type command. Also, only one PRI group can be configured on a controller.
Step 14	exit Example: Router(config-controller)# exit	Exits controller configuration mode and completes the process for adding back the PRI groups or DS0 groups.
Step 15	Repeat Step 3, then continue with Step 16.	--
Step 16	no shutdown Example: Router(config-controller)# no shutdown	Saves the controller configurations on the slot and port specified.
Step 17	end Example: Router(config-controller)# end	Exits controller configuration mode and completes the process for bringing the T1 controller back up.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    voice-card slot

4.    codec complexity flex [reservation - fixed {high | medium}]

5.    voice local-bypass

6.    exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	voice-card slot Example: Router(config)# voice-card 1	Enters voice-card configuration mode and specifies the slot location. For the slotargument, specify a value from 1 to 4, depending on your router.
Step 4	codec complexity flex [reservation - fixed {high | medium}] Example: Router(config-voicecard)# codec complexity flex	Specifies the flex option for codec complexity. flex --Up to 16 calls can be completed per DSP. The number of supported calls varies from 6 to 16, depending on the codec used for a call. In this mode, reservation for analog VICs may be needed for certain appplications such as CAMA E-911 calls because oversubscription of DSPs is possible. If this is true, then the reservation-fixed option may be enabled. There is no reservation by default. reservation-fixed--Appears as an option only when there is an analog VIC present. Ensures that sufficient DSP resources are available to handle a call. If you enter this keyword, then specify if the complexity should be high or medium. Note    You cannot change codec complexity while DS0 groups are defined. If they are already set up, perform the steps in the Changing Codec Complexity.
Step 5	voice local-bypass Example: Router(config-voicecard)# voice local-bypass	Configures local calls to bypass the DSP. This is the default. Using this command enables intranetwork-module hairpinning (no DSPs). Note    For POTS-to-POTS calls between two network modules, hairpinning is not supported. If the connection manager in Cisco IOS software does not automatically handle this, it might be necessary to disable local-bypass so that DSPs are used for these calls.
Step 6	exit Example: Router(config-voicecard)# exit	Exits voice-card configuration mode and returns the router to global configuration mode.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.   Do one of the following:

4.    codec {high | medium} [ecan-extended]

5.    exit

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	Do one of the following: dspint dspfarm slot /0 dspint dspfarm slot / port-adapter / port Example: Router(config)# dspint dspfarm 2/0	Enters DSP interface configuration mode for the Cisco 7200 series. or Enters DSP interface configuration mode for the Cisco 7500 series.
Step 4	codec {high | medium} [ecan-extended] Example: Router(config-dspfarm)# codec medium ecan-extended	Sets the codec complexity. The optional ecan-extended keyword selects the G.168 extended echo canceller. This keyword is supported only in Cisco IOS Release 12.2(13)T. For more information, see the "How to Configure the Extended G.168 Echo Canceller" section. This command affects the choice of codecs available when the codec command is used in dial-peer configuration mode.
Step 5	exit Example: Router(config-dspfarm)# exit	Exits to global configuration mode.

What to Do Next

Cisco 7200 Series:

On the Cisco 7200 series, the PA-MCX-2TE1 port adapter (PA) card can be used for making voice calls. This PA does not have any DSPs but uses the DSP resources of the PA-VXC-2TE1+ card present in another slot. If the PA-MCX card is used, codec complexity is configured for PA-VXC, while all other echo cancellation configurations are done for PA-MCX.

The PA-MCX card borrows the DSP resources from the PA-VXC, PA-VXB, or PA-VXA card. If one of the PA-VXC, PA-VXB, or PA-VXA cards has extended echo cancellation configured on the DSP interface, extended echo cancellation is enabled for the PA-MCX card. It is recommended that you have the same codec complexity and echo cancellation configuration on all the PA-VXC, PA-VXB, or PA-VXA cards in the router.

Cisco AS5300:

Codec support on the Cisco AS5300 is determined by the capability list on the voice feature card, which defines the set of codecs that can be negotiated for a voice call. The capability list is created and populated when VCWare is unbundled and DSPWare is added to VFC flash memory. The capability list does not indicate codec preference; it simply reports the codecs that are available. The session application decides which codec to use. Codec support is configured on dial peers rather than on voice ports; refer to the "Dial Peer Configuration on Voice Gateway Routers" document.

Cisco AS5800:

Codec support is selected on Cisco AS5800 access servers during dial peer configuration. Refer to the "Dial Peer Configuration on Voice Gateway Routers" document.

The framing format parameter describes the way that bits are robbed from specific frames to be used for signaling purposes. The controller must be configured to use the same framing format as the line from the PBX or CO that connects to the voice port you are configuring.

Digital T1 lines use SF or ESF framing formats. SF provides two-state, continuous supervision signaling, in which bit values of 0 are used to represent on-hook and bit values of 1 are used to represent off-hook. ESF robs four bits instead of two, yet has little impact on voice quality. ESF is required for 64-kbps operation on DS0 and is recommended for PRI configurations.

E1 lines can be configured for CRC4 or no cyclic redundancy check, with an optional argument for E1 lines in Australia.

Digital T1/E1 interfaces use timers called clocks to ensure that voice packets are delivered and assembled properly. All interfaces handling the same packets must be configured to use the same source of timing so that packets are not lost or delivered late. The timing source that is configured can be external (from the line) or internal to the router's digital interface.

If the timing source is internal, timing derives from the onboard phase-lock loop (PLL) chip in the digital voice interface. If the timing source is line (external), then timing derives from the PBX or PSTN CO to which the voice port is connected. It is generally preferable to derive timing from the PSTN becauseits clocks are maintained at an extremely accurate level. This is the default setting for the clocks. When two or more controllers are configured, one should be designated as the primary clock source; it will drive the other controllers.

The line keyword specifies that the clock source is derived from the active line rather than from the free-running internal clock. The following rules apply to clock sourcing on the controller ports:

• When both ports are set to line clocking with no primary specification, port 0 is the default primary clock source and port 1 is the default secondary clock source.
• When both ports are set to line and one port is set as the primary clock source, the other port is by default the backup or secondary source and is loop-timed.
• If one port is set to clock source line or clock source line primary and the other is set to clock source internal, the internal port recovers clock from the clock source line port if the clock source line port is up. If it is down, then the internal port generates its own clock.
• If both ports are set to clock source internal, there is only one clock source: internal.

This section describes the five basic timing scenarios that can occur when a digital voice port is connected to a PBX or CO. In all the examples that follow, the PSTN (or CO) and the PBX are interchangeable for purposes of providing or receiving clocking.

• Single voice port providing clocking--In this scenario, the digital voice hardware is the clock source for the connected device, as shown in the figure below. The PLL generates the clock internally and drives the clocking on the line. Generally, this method is useful only when connecting to a PBX, key system, or channel bank. A Cisco VoIP gateway rarely provides clocking to the CO because CO clocking is much more reliable. The following configuration sets up this clocking method for a digital E1 voice port:

controller E1 1/0
 framing crc4
 linecoding hdb3
 clock source internal
 ds0-group timeslots 1-15 type e&m-wink-start

• Single voice port receiving internal clocking--In this scenario, the digital voice hardware receives clocking from the connected device (CO telephony switch or PBX) (see the figure below). The PLL clocking is driven by the clock reference on the receive (Rx) side of the digital line connection.

The following configuration sets up this clocking method:

controller T1 1/0
 framing esf
 linecoding ami
 clock source line
 ds0-group timeslots 1-12 type e&m-wink-start

• Dual voice ports receiving clocking from the Line--In this scenario, the digital voice port has two reference clocks, one from the PBX and another from the CO, as shown in the figure below.

Because the PLL can derive clocking from only one source, this case is more complex than the two preceding examples. Before looking at the details, consider the following as they pertain to the clocking method:

• • Looped-time clocking--The voice port takes the clock received on its Rx (receive) pair and regenerates it on its Tx (transmit) pair. While the port receives clocking, the port is not driving the PLL on the card but is "spoofing" (that is, fooling) the port so that the connected device has a viable clock and does not see slips (that is, loss of data bits). PBXs are not designed to accept slips on a T1 or E1 line, and such slips cause a PBX to drop the link into failure mode. While in looped-time mode, the router often sees slips, but because these are controlled slips, they usually do not force failures of the router's voice port.
  • Slips--These messages indicate that the voice port is receiving clock information that is out of phase (out of synchronization). Because the router has only a single PLL, it can experience controlled slips while it receives clocking from two different time sources. The router can usually handle controlled slips because its single-PLL architecture anticipates them.

Note	Physical layer issues, such as bad cabling or faulty clocking references, can cause slips. Eliminate these slips by addressing the physical layer or clock reference problems.

In the dual voice ports receiving clocking from the line scenario, the PLL derives clocking from the CO and puts the voice port connected to the PBX into looped-time mode. This is usually the best method because the CO provides an excellent clock source (and the PLL usually requires that the CO provide that source) and a PBX usually must receive clocking from the other voice port.

The following configuration sets up this clocking method (controller E1 1/0 is connected to the CO; controller E1 1/1 is connected to the PBX:

controller E1 1/0
 framing crc4
 linecoding hdb3
 clock source line primary
 ds0-group timeslots 1-15 type e&m-wink-start
!
controller E1 1/1
 framing crc4
 linecoding hdb3
 clock source line
 ds0-group timeslots 1-15 type e&m-wink-start

The clock source line primary command tells the router to use this voice port to drive the PLL. All other voice ports configured as clock source line are then put into an implicit loop-timed mode. If the primary voice port fails or goes down, the other voice port instead receives the clock that drives the PLL. In this configuration, port 1/1 might see controlled slips, but these should not force it down. This method prevents the PBX from seeing slips.

Note

When two T1/E1 lines terminate on a two-port interface card, such as the VWIC-2MFT, and both controllers are set for line clocking but the lines are not within clocking tolerance of one another, one of the controllers is likely to experience slips. To prevent slips, ensure that the two T1 or E1 lines are within clocking tolerance of one another, even if the lines are from different providers.

• Dual voice ports (one receives clocking and one provides clocking)--In this scenario, the digital voice hardware receives clocking for the PLL from E1 0 and uses this clock as a reference to clock E1 1 (see the figure below). If controller E1 0 fails, the PLL internally generates the clock reference to drive E1 1.

The following configuration sets up this clocking method:

controller E1 1/0
 framing crc4
 linecoding hdb3
 clock source line 
 ds0-group timeslots 1-15 type e&m-wink-start
!
controller E1 1/1
 framing crc4
 linecoding hdb3
 clock source internal
 ds0-group timeslots 1-15 type e&m-wink-start

• Dual voice ports (router provides both clocks)--In this scenario, the router generates the clock for the PLL and, therefore, for both voice ports (see the figure below).

The following configuration sets up this clocking method:

controller E1 1/0
 framing crc4
 linecoding hdb3
 clock source internal
 ds0-group timeslots 1-15 type e&m-wink-start
!
controller E1 1/1
 framing esf
 linecoding b8zs
 clock source internal
 ds0-group timeslots 1-15 type e&m-wink-start

Voice systems that pass digitized (pulse code modulation or PCM) speech have always relied on the clocking signal being embedded in the received bit stream. This reliance allows connected devices to recover the clock signal from the bit stream, and then use this recovered clock signal to ensure that data on different channels keep the same timing relationship with other channels.

If a common clock source is not used between devices, the binary values in the bit streams may be misinterpreted because the device samples the signal at the wrong moment. As an example, if the local timing of a receiving device is using a slightly shorter time period than the timing of the sending device, a string of eight continuous binary 1s may be interpreted as nine continuous 1s. If this data is then re-sent to further downstream devices that used varying timing references, the error could be compounded. By ensuring that each device in the network uses the same clocking signal, you can ensure the integrity of the traffic.

If timing between devices is not maintained, a condition known as clock slip can occur. Clock slip is the repetition or deletion of a block of bits in a synchronous bit stream due to a discrepancy in the read and write rates at a buffer.

Slips are caused by the inability of an equipment buffer store (or other mechanisms) to accommodate differences between the phases or frequencies of the incoming and outgoing signals in cases where the timing of the outgoing signal is not derived from that of the incoming signal.

A T1 or E1 interface sends traffic inside repeating bit patterns called frames. Each frame is a fixed number of bits, allowing the device to see the start and end of a frame. The receiving device also knows exactly when to expect the end of a frame simply by counting the appropriate number of bits that have come in. Therefore, if the timing between the sending and receiving device is not the same, the receiving device may sample the bit stream at the wrong moment, resulting in an incorrect value being returned.

Even though Cisco IOS software can be used to control the clocking on these platforms, the default clocking mode is effectively free running, meaning that the received clock signal from an interface is not connected to the backplane of the router and used for internal synchronization between the rest of the router and its interfaces. The router will use its internal clock source to pass traffic across the backplane and other interfaces.

For data applications, this clocking generally does not present a problem as a packet is buffered in internal memory and is then copied to the transmit buffer of the destination interface. The reading and writing of packets to memory effectively removes the need for any clock synchronization between ports.

Digital voice ports have a different issue. It would appear that unless otherwise configured, Cisco IOS software uses the backplane (or internal) clocking to control the reading and writing of data to the DSPs. If a PCM stream comes in on a digital voice port, it will be using the external clocking for the received bit stream. However, this bit stream will not necessarily be using the same reference as the router backplane, meaning the DSPs may misinterpret the data coming in from the controller.

This clocking mismatch is seen on the router's E1 or T1 controller as a clock slip--the router is using its internal clock source to send the traffic out the interface but the traffic coming in to the interface is using a completely different clock reference. Eventually, the difference in the timing relationship between the transmit and receive signal becomes so great that the controller registers a slip in the received frame.

To eliminate the problem, change the default clocking behavior through Cisco IOS configuration commands. It is absolutely critical to set up the clocking commands properly.

Even though these commands are optional, we strongly recommend you enter them as part of your configuration to ensure proper network clock synchronization:

network-clock-participate [slot slot-number | wic wic-slot | aim aim-slot-number network-clock-select priority{bri | t1 | e1} slot / port

The network-clock-participate command allows the router to use the clock from the line via the specified slot/WIC/AIM and synchronize the onboard clock to the same reference.

If multiple VWICS are installed, the commands must be repeated for each installed card. The system clocking can be confirmed using the show network clocks command.

Caution

If you are configuring a Cisco 2600 XM voice gateway with an NM-HDV2 or NM-HD-2VE installed in slot 1, do not use the network-clock-participate slot 1 command in the configuration. In this particular hardware scenario, the network-clock-participate slot 1 command is not necessary. If the network-clock-participate slot 1 command is configured, voice and data connectivity on interfaces terminating on the NM-HDV2 or NM-HD-2VE network module may fail to operate properly. Data connectivity to peer devices may not be possible, and even loopback plug tests to the serial interface spawned via a channel group configured on the local T1/E1 controller will fail. Voice groups such as CAS DS0 groups and ISDN PRI groups may fail to signal properly. The T1/E1 controller may accumulate large amounts of timing slips and Path Code Violations (PCVs) and Line Code Violations (LCVs).

Digital T1/E1 interfaces require that line encoding be configured to match that of the PBX or CO that is being connected to the voice port. Line encoding defines the type of framing used on the line.

T1 line encoding methods include AMI and B8ZS. AMI is used on older T1 circuits and references signal transitions with a binary 1, or "mark." B8ZS, a more reliable method, is more popular and is recommended for PRI configurations as well. B8ZS encodes a sequence of eight zeros in a unique binary sequence to detect line-coding violations.

Supported E1 line encoding methods are AMI and HDB3, which is a form of zero-suppression line coding.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.    card type {t1 | e1} slot

4.   Do one of the following:

5.   Do one of the following:

6.    clock source {line [primary | secondary] | internal}

7.   Do one of the following:

8.    ds0-group ds0-group-number timeslots timeslot-list type {e&m-delay-dial | e&m-fgd | e&m-immediate-start|e&m-wink-start | ext-sig | fgd-eana | fxo-ground-start | fxo-loop-start | fxs-ground-start | fxs-loop-start}

9.    no shutdown

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	card type {t1 | e1} slot Example: Router(config)# card type t1 0	Defines the card as T1 or E1 and identifies the location.
Step 4	Do one of the following: controller {t1 | e1} slot / port controller {t1 | e1} number controller {t1 | e1} shelf / slot / port Example: Router(config)# controller t1 1/0 Example: Example: Router(config)# controller t1 1 Example: or Example: Router(config)# controller t1 1/0/0	Enters controller configuration mode and specifies either T1 or E1 for the line. For the Cisco 2600, Cisco 3600 series, Cisco MC3810, and Cisco 7200 series, identifies the slot and port. For the Cisco AS5300, identifies the port number. For the Cisco AS5800 and Cisco 7500 series, identifies the shelf, slot, and port number.
Step 5	Do one of the following: framing {sf | esf} framing {crc4 | no-crc4} [australia] Example: Router(config-controller)# framing esf Example: Example: Example: Router(config-controller)# framing crc4	Selects frame type for T1 or E1 line. For T1, the frame type can be sf or esf. Default for T1 is sf. For E!, the frame type can be crc4 or no crc4 or australia. Default for E1 is crc4.
Step 6	clock source {line [primary | secondary] | internal} Example: Router(config-controller)# clock source line primary	Configures the clock source. Default is line. For more information about clock sources, see the Clock Sources on Digital T1 E1 Voice Ports.
Step 7	Do one of the following: linecode {ami | b8zs} linecode {ami | hdb3} Example: Router(config-controller)# linecode b8zs Example: Example: Router(config-controller)# linecode hdb3	Specifies the line encoding to use for T1 or E1 line. For T1, the line encoding can be ami or b8zs. Default for T1 is ami. For E1, the line encoding can be ami or hdb3. Default for E1 is hdb3.
Step 8	ds0-group ds0-group-number timeslots timeslot-list type {e&m-delay-dial | e&m-fgd | e&m-immediate-start|e&m-wink-start | ext-sig | fgd-eana | fxo-ground-start | fxo-loop-start | fxs-ground-start | fxs-loop-start} Example: Router(config-controller)# ds0-group 30 timeslots 0 type e&m-immediate-start	Defines the T1 channels for use by compressed voice calls and the signaling method that the router uses to connect to the PBX or CO. Note    This step shows the basic syntax and signaling types available with the ds0-group command. For the complete syntax, refer to the Cisco IOS Voice Command Reference.
Step 9	no shutdown Example: Router(config-controller)# no shutdown	Activates the controller.

SUMMARY STEPS

1.    enable

2.    configure terminal

3.   Do one of the following:

4.    type {1 | 2 | 3 | 5}

5.    cptone locale

6.    compand-type {u-law | a-law}

7.    ring frequency {25 | 50}

8.    ring number number

9.    ring cadence {[pattern01 | pattern02 | pattern03 | pattern04 | pattern05 | pattern06 | pattern07 | pattern08 | pattern09 | pattern10 | pattern11 | pattern12] [define pulse interval]}

10.    description string

11.    no shutdown

DETAILED STEPS

	Command or Action	Purpose
Step 1	enable Example: Router> enable	Enables privileged EXEC mode. Enter your password if prompted.
Step 2	configure terminal Example: Router# configure terminal	Enters global configuration mode.
Step 3	Do one of the following: voice-port port voice-port slot / port:ds0-group-number voice-port slot / port-adapter :ds0-group-number voice-port slot / port-adapter/slot :ds0-group-number voice-port controller :{ds0-group-number | D} voice-port slot / controller :{ds0-group-number | D} voice-port shelf / slot / port:ds0-group-number Example: Router(config)# voice-port 1:0 Example: Example: Router(config)# voice-port 1/1:0 Example: Router(config)# voice-port 1/1/1:1 Example: Router(config)# voice-port 1:1 Example: Router(config)# voice-port 1/0 D Example: Router(config)# voice-port 1/2/0:1	Enters voice-port configuration mode and identifies the port to be configured. For the Cisco 880 series, specify the port number. For the Cisco 2600, Cisco 3600, and Cisco 3700 series, specify the slot, port, and DS0 group number. For the Cisco 7200 series, specify the slot, port adapter,and DS0 group number. For the Cisco 7500 series, specify the slot, port adapter, slot, and DS0 group number. For the Cisco AS5300, specify the controller and DS0 group number or the keyword D. For the Cisco AS5350, Cisco AS5400, and Cisco AS5850 universal gateways, specify the slot, controller, and DS0 group number or the keyword D. For the Cisco AS5800, specify the shelf, slot, port, and DS0 group number.
Step 4	type {1 | 2 | 3 | 5} Example: Router(config-voiceport)# type 1	(E&M only) Specifies the type of E&M interface to which this voice port is connected. See Table 3 in the "Voice Port Configuration Overview" chapter for an explanation of E&M types. Default is 1.
Step 5	cptone locale Example: Router(config-voiceport)# cptone us	Selects a two-letter locale keyword for the voice call progress tones and other locale-specific parameters to be used on this voice port. Voice call progress tones include dial tone, busy tone, and ringback tone, which vary with geographical region. Other parameters include ring cadence and compand type. Cisco routers comply with the ISO3166 locale name standards; to see valid choices, enter a question mark (?) following the cptone command. Default is us.
Step 6	compand-type {u-law | a-law} Example: Router(config-voiceport)# compand-type u-law	(Cisco 2600 and Cisco 3600 series routers.) Specifies the companding standard used. This command is used in cases when the DSP is not used, such as local cross-connects, and overwrites the compand-type value set by the cptone command. The default for E1 is a-law. The default for T1 is u-law. Note    If you have a Cisco 3660 router, the compand-type a-law command must be configured on the analog ports only. The Cisco 2660, 3620, and 3640 routers do not require the compand-type a-law command configured. However, if you request a list of commands, the compand-type a-law command will display.
Step 7	ring frequency {25 | 50} Example: Router(config-voiceport)# ring frequency 50	(FXS only) Selects the ring frequency, in hertz, used on the FXS interface. This number must match the connected telephony equipment, and can be country-dependent. If the ring frequency is not set properly, the attached telephony device may not ring or it may buzz. Default is 25.
Step 8	ring number number Example: Router(config-voiceport)# ring number 1	(FXO only) Specifies the maximum number of rings to be detected before an incoming call is answered by the router. Default is 1.
Step 9	ring cadence {[pattern01 | pattern02 | pattern03 | pattern04 | pattern05 | pattern06 | pattern07 | pattern08 | pattern09 | pattern10 | pattern11 | pattern12] [define pulse interval]} Example: Router(config-voiceport)# ring cadence pattern01 define 12 15	(FXS only) Specifies an existing pattern for ring, or defines a new one. Each pattern specifies a ring-pulse time and a ring-interval time. The keywords and arguments are as follows: pattern01 through pattern12--Specifies preset ring cadence patterns. Enter ring cadence ? to see ring pattern explanations. define pulse interval --Specifies a user-defined pattern as follows: pulse is a number (1 or 2 digits from 1 to 50) specifying ring pulse (on) time in hundreds of milliseconds. interval is a number (1 or 2 digits from 1 to 50) specifying ring interval (off) time in hundreds of milliseconds. The default is the pattern specified by the configured cptone locale command.
Step 10	description string Example: Router(config-voiceport)# description 1	Attaches a text string to the configuration that describes the connection for this voice port. This description appears in various displays and is useful for tracking the purpose or use of the voice port. The string argument is a character string from 1 to 255 characters in length. The default is that no description is attached to the configuration.
Step 11	no shutdown Example: Router(config-voiceport)# no shutdown	Activates the voice port.