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This chapter provides information about trunk types. In a distributed call-processing environment, Cisco Unified Communications Manager communicates with other Cisco Unified Communications Manager clusters, the public switched telephone network (PSTN), and other non-IP telecommunications devices, such as private branch exchanges (PBXs) by using trunk signaling protocols and voice gateways.
For SIP Trunks follow these steps:
Trunk configuration in Cisco Unified Communications Manager Administration depends on the network design and call-control protocols that are used in the IP WAN. All protocols require that either a signaling interface (trunk) or a gateway be created to accept and originate calls. For some IP protocols, such as MGCP, you configure trunk signaling on the gateway. You specify the type of signaling interface when you configure the gateway in Cisco Unified Communications Manager. For example, to configure QSIG connections to Cisco Unified Communications Manager, you must add an MGCP voice gateway that supports QSIG protocol to the network. You then configure the T1 PRI or E1 PRI trunk interface to use the QSIG protocol type. For more information about configuring gateways, see the Cisco Unified Communications Manager Voice Gateways Overview.
In addition to using gateways to route calls, you can configure trunks in Cisco Unified Communications Manager Administration to function as described in the sections which follow.
Gatekeepers that are used in a distributed call-processing environment provide call routing and call admission control for Cisco Unified Communications Manager clusters. Intercluster trunks that are gatekeeper-controlled can communicate with all remote clusters. Similarly, an H.225 trunk can communicate with any H.323 gatekeeper-controlled endpoints including Cisco Unified Communications Manager clusters. Route patterns or route groups can route the calls to and from the gatekeeper. In a distributed call-processing environment, the gatekeeper uses the E.164 address (phone number) and determines the appropriate IP address for the destination of each call, and the local Cisco Unified Communications Manager uses that IP address to complete the call.
For large distributed networks where many Cisco Unified Communications Manager clusters exist, you can avoid configuring individual intercluster trunks between each cluster by using gatekeepers.
When you configure gatekeeper-controlled trunks, Cisco Unified Communications Manager creates a virtual trunk device. The gatekeeper changes the IP address of this device dynamically to reflect the IP address of the remote device. Specify these trunks in the route patterns or route groups that route calls to and from the gatekeeper.
See Cisco Unified Communications Solution Reference Network Design (SRND) for more detailed information about gatekeeper configuration, dial plan considerations when using a gatekeeper, and gatekeeper interaction with Cisco Unified Communications Manager.
With no gatekeepers in the distributed call-processing environment, you must configure a separate intercluster trunk for each remote device pool in a remote cluster that the local Cisco Unified Communications Manager can call over the IP WAN. You also configure the necessary route patterns and route groups to route calls to and from the various intercluster trunks. The intercluster trunks statically specify the IP addresses of the remote devices.
Your choices for configuring trunks in Cisco Unified Communications Manager depend on whether the IP WAN uses gatekeepers to handle call routing. Also, the types of call-control protocols that are used in the call-processing environment determine trunk configuration options.
You can configure the trunk types in Cisco Unified Communications Manager Administration listed in this section.
In an H.323 network that uses gatekeepers, use an H.225 trunk with gatekeeper control to configure a connection to a gatekeeper for access to other Cisco Unified Communications Manager clusters and to H.323 devices. An H.225 trunk can communicate with any H.323 gatekeeper-controlled endpoint. When you configure an H.323 gateway with gatekeeper control in Cisco Unified Communications Manager Administration, use an H.225 trunk. To choose this method, use and choose H.225 Trunk (Gatekeeper Controlled).
You also configure route patterns and route groups to route calls to and from the gatekeeper. For more information, see the Configure Gatekeepers and Trunks.
In a distributed call-processing network with gatekeepers, use an intercluster trunk with gatekeeper control to configure connections between clusters of Cisco Unified Communications Manager systems. Gatekeepers provide call admission control and address resolution for intercluster calls. A single intercluster trunk can communicate with all remote clusters. To choose this method, use and choose Inter-Cluster Trunk (Gatekeeper Controlled) in Cisco Unified Communications Manager Administration.
You also configure route patterns and route groups to route the calls to and from the gatekeeper. In this configuration, the gatekeeper dynamically determines the appropriate IP address for the destination of each call, and the local Cisco Unified Communications Manager uses that IP address to complete the call
For more information about gatekeepers, see the Configure Gatekeepers and Trunks.
Intercluster trunks support location-based call admission control (CAC) through use of the specially designated Phantom location. See Location-Based Call Admission Control Over Intercluster Trunk for additional information.
In a distributed network that has no gatekeeper control, you must configure a separate intercluster trunk for each device pool in a remote cluster that the local Cisco Unified Communications Manager can call over the IP WAN. The intercluster trunks statically specify the IP addresses or host names of the remote devices. To choose this method, use and choose Inter-Cluster Trunk (Non-Gatekeeper Controlled) in Cisco Unified Communications Manager Administration.
Note | You must specify the IP addresses of all remote Cisco Unified Communications Manager nodes that belong to the device pool of the remote non-gatekeeper-controlled intercluster trunk. |
You also configure the necessary route patterns and route groups to route calls to and from the intercluster trunks.
Intercluster trunks support location-based call admission control (CAC) through use of the specially designated Phantom location. See Location-Based Call Admission Control Over Intercluster Trunk for additional information.
In a call-processing environment that uses Session Initiation Protocol (SIP), use SIP trunks to configure a signaling interface with Cisco Unified Communications Manager for SIP calls. SIP trunks (or signaling interfaces) connect Cisco Unified Communications Manager clusters with a SIP proxy server. The SIP signaling interface uses requests and responses to establish, maintain, and terminate calls (or sessions) between two or more endpoints.
To configure a SIP trunk in Cisco Unified Communications Manager Administration, choose and then SIP Trunk.
Tip | You must also configure route groups and route patterns that use the SIP trunks to route the SIP calls. |
To receive QSIG basic calls and features, such as MWI, Call Transfer, Call Diversion, Call Completion, Path Replacement, and Identification Services, across an intercluster SIP trunk or a SIP gateway, configure a SIP trunk with QSIG as the tunneled protocol.
Note | Remote-Party-ID (RPID) headers coming in from the SIP gateway can interfere with QSIG content and cause unexpected behavior with Call Back capabilities. To prevent interference with the QSIG content, turn off the RPID headers on the SIP gateway. |
To turn off RPID headers on the SIP gateway, apply a SIP profile to the voIP dial peer on the gateway, as shown in the following example:
voice class sip-profiles 1000 request ANY sip-header Remote-Party_ID remove response ANY sip-header Remote-Party-ID remove dial-peer voice 124 voip destination-pattern 3... signaling forward unconditional session protocol sipv2 session target ipv4:<ip address> voice-class sip profiles 1000
SIP trunks support location-based call admission control (CAC) through use of the specially designated Phantom location.
Note | When you create a SIP trunk with Cisco Intercompany Media Engine (IME) selected as the trunk service type, the default for the Tunneled Protocol field is QSIG. QSIG must be the tunneled protocol for QSIG features to work on a Cisco IME trunk. For more information about Cisco IME, see the Cisco Intercompany Media Engine Installation and Configuration Guide. |
In line with E.164 standards, calling party normalization enhances the dialing capabilities of some phones and improves call back functionality when a call is routed to multiple geographical locations; that is, the feature ensures that the called party can return a call without needing to modify the directory number in the call log directories on the phone. Additionally, calling party normalization allows you to globalize and localize phone numbers, so the appropriate calling number presentation displays on the phone.
Configuring calling party normalization alleviates issues with toll bypass where the call is routed to multiple locations over the IP WAN. In addition, it allows Cisco Unified Communications Manager to distinguish the origin of the call to globalize or localize the calling party number for the phone user.
SIP trunks and MGCP gateways can support sending the international escape character, +, for calls. H.323 gateways/trunks do not support the + because the H.323 protocol does not support the international escape character, +. QSIG trunks do not attempt to send the +. For outgoing calls through a gateway that supports +, Cisco Unified Communications Manager can send the + with the dialed digits to the gateway/trunk. For outgoing calls through a gateway/trunk that does not support +, the international escape character + gets stripped when Cisco Unified Communications Manager sends the call information to the gateway/trunk.
SIP does not support the number type, so calls through SIP trunks only support the Incoming Calling Party Unknown Number (prefix and digits-to-strip) settings.
You can configure the international escape character, +, to globalize the calling party number. For information on the international escape character, +, see Use the International Escape Character.
The H.323 protocol does not support the international escape character, +. To ensure that correct prefixes, including the international escape character, +, get applied for inbound calls over H.323 gateways/trunks, you must configure the incoming called party settings in the service parameter, device pool, H.323 gateway, or H.323 trunk windows; that is, configuring the incoming called party settings ensures that when a inbound call comes from a H.323 gateway or trunk, Cisco Unified Communications Manager transforms the called party number back to the value that was originally sent over the trunk/gateway.
For example, to ensure that the correct DN patterns get used with SAF/call control discovery for inbound calls over H.323 gateways/trunks, you must configure the incoming called party settings in the service parameter, device pool, or H.323 (non-gatekeeper controlled) trunk window. See the following example for more information.
A caller places a call to +19721230000 to Cisco Unified Communications Manager A.
Cisco Unified Communications Manager A receives +19721230000 and transforms the number to 55519721230000 before sending the call to the H.323 trunk. In this case, your configuration indicates that the international escape character + should be stripped and 555 should be prepended for calls of International type.
For this inbound call from the trunk, Cisco Unified Communications Manager B receives 55519721230000 and transforms the number back to +19721230000 so that digit analysis can use the value as it was sent by the caller. In this case, your configuration for the incoming called party settings indicates that you want 555 to be stripped and +1 to be prepended to called party numbers of International type.
You can configure the incoming called party settings in the service parameter, device pool, H.323 gateway, or H.323 (gatekeeper-controlled) windows.
The service parameters support the Cisco CallManager service. To configure the service parameters, click Advanced in the Service Parameter Configuration window for the Cisco CallManager service; then, locate the H.323 pane for the following parameters:
Incoming Called Party National Number Prefix - H.323
Incoming Called Party International Number Prefix - H.323
Incoming Called Party Subscriber Number Prefix - H.323
Incoming Called Party Unknown Number Prefix - H.323
These service parameters allow you to prefix digits to the called number based on the Type of Number field for the inbound offered call. You can also strip a specific number of leading digits before the prefix gets applied. To prefix and strip digits by configuring these parameter fields, use the following formula, x:y, where x represents the exact prefix that you want to add to called number and y represents the number of digits stripped; be aware that the colon separates the prefix and the number of stripped digits. For example, enter 91010:6 in the field, which means that you want to strip 6 digits and then add 901010 to the beginning of the called number. In this example, a national call of 2145551234 becomes 910101234. You can strip up to 24 digits and prefix/add up to than 16 digits.
Using Cisco Unified Communications Manager Administration, you can configure trunks as OnNet (internal) trunks or OffNet (external) trunks by using Trunk Configuration or by setting a clusterwide service parameter. Used in conjunction with the clusterwide service parameter, Block OffNet to OffNet Transfer, the configuration determines whether calls can be transferred over a trunk.
To use the same trunk to route both OnNet and OffNet calls, associate the trunk with two different route patterns. Make one trunk OnNet and the other OffNet with both having the Allow Device Override check box unchecked.
Using Cisco Unified Communications Manager Administration Trunk Configuration, you can configure a trunk as OffNet or OnNet. The system considers calls that are coming to the network through that trunk as OffNet or OnNet, respectively. Use the Trunk Configuration window field, Call Classification, to configure the trunk as OffNet, OnNet, or Use System Default. See the following table for a description of these settings.
The Route Pattern Configuration window provides a drop-down list box called Call Classification, which allows you to configure a route pattern as OffNet or OnNet. When Call Classification is set to OffNet and the Allow Device Override check box is unchecked, the system considers the outgoing calls that use this route pattern as OffNet (if configured as OnNet and check box is unchecked, outgoing calls are considered OnNet).
You can use the same trunk to route both OnNet and OffNet calls by associating the trunk with two different route patterns: one OnNet and the other OffNet, with both having the Allow Device Override check box unchecked. For outgoing calls, the outgoing device setting classifies the call as either OnNet or OffNet by determining whether the Allow Device Override check box is checked.
In route pattern configuration, if the Call Classification is set as OnNet, the Allow Device Override check box is checked, and the route pattern is associated with an OffNet Trunk, the system considers the outgoing call as OffNet.
Setting Name |
Description |
---|---|
OffNet |
This setting identifies the trunk as being an external trunk. When a call comes in from a trunk that is configured as OffNet, the outside ring gets sent to the destination device. |
OnNet |
This setting identifies the trunk as being an internal trunk. When a call comes in from a trunk that is configured as OnNet, the inside ring gets sent to the destination device. |
Use System Default |
This setting uses the Cisco Unified Communications Manager clusterwide service parameter Call Classification. |
To configure all trunks to be OffNet (external) or OnNet (internal), perform the following two steps:
Block transfer restricts the transfer between external devices, so fraudulent activity gets prevented. You can configure the following devices as OnNet (internal) or OffNet (external) to Cisco Unified Communications Manager:
If you do not want OffNet calls to be transferred to an external device (one that is configured as OffNet), set the Cisco Unified Communications Manager clusterwide service parameter, Block OffNet to OffNet Transfer, to True.
If a user tries to transfer a call on an OffNet trunk that is configured as blocked, a message displays on the user phone to indicate that the call cannot be transferred.
To find route groups that use a specific trunk, choose Dependency Records from the Related Links drop-down list box that is provided on the Cisco Unified Communications Manager Administration Trunk Configuration window. The Dependency Records Summary window displays information about route groups that are using the trunk. To find more information about the route group, click the route group, and the Dependency Records Details window displays. If the dependency records are not enabled for the system, the dependency records summary window displays a message.
This feature allows Cisco Unified Communications Manager trunks to transparently pass through the shared secret (Diffie-Hellman key) and other H.235 data between two H.235 endpoints so that the two endpoints can establish a secure media channel.