AudioCodes Mediant 1000B - Alternative Routing for IP-To-Tel Calls; Alternative Routing to Trunk Upon Q.931 Call Release Cause Code

Version 7.2 535 Mediant 1000B Gateway & E-SBC
User's Manual 24. Routing
24.5 Alternative Routing for IP-to-Tel Calls
The device supports alternative IP-to-Tel call routing, as described in this section.
24.5.1 Alternative Routing to Trunk upon Q.931 Call Release Cause
Code
You can configure up to 10 ISDN Q.931 release cause codes, which if received from the
Tel side, the device routes the IP-to-Tel call to an alternative Trunk Group, if configured.
Alternative IP-to-Tel routing rules are configured in the IP-to-Tel Routing table. These rules
must be configured anywhere below the "main" routing rule and with identical matching
characteristics (e.g., destination prefix number) to the "main" routing rule. The device uses
the first alternative route that is available. For more information on configuring alternative
IP-to-Tel routing rules in the IP-to-Tel Routing table, see ''Configuring IP-to-Tel Routing
Rules'' on page 520.
A release cause code indicates that the IP-to-Tel call has been rejected or disconnected on
the Tel side. The release cause codes are configured in the Reasons for IP-to-Tel
Alternative Routing table. For example, you can configure alternative IP-to-Tel routing for
scenarios where the initial Tel destination is busy and a Q.931 Cause Code No. 17 is
received (or for other call releases that issue the default Cause Code No. 3).
You can configure a default release cause code that the device issues itself upon the
following scenarios:

The device initiates a call release whose cause is unknown.

No free channels (i.e., busy) in the Trunk Group.

No appropriate routing rule located in the IP-to-Tel Routing table.

Phone number is not located in the IP-to-Tel Routing table.
The default release code is Cause Code No. 3 (No Route to Destination). You can change
the default code as follows:
 To change the default Q.931 release code:
1. Open the Gateway Advanced Settings page (Setup menu > Signaling & Media tab >
Gateway folder > Gateway Advanced Settings).
2. In the 'Default Release Cause' field, enter the release cause code:
Figure 24-11: Configuring Default Q.931 Release Cause Code
3. Click Apply.
Note:
• If a Trunk is disconnected or not synchronized, the device issues itself the internal
Cause Code No. 27. This cause code is mapped (by default) to SIP 502.
• The default release cause is described in the Q.931 notation and translated to
corresponding SIP 40x or 50x values (e.g., Cause Code No. 3 to SIP 404, and
Cause Code No. 34 to SIP 503).
• For analog interfaces: For information on mapping PSTN release causes to SIP
responses, see PSTN Release Cause to SIP Response Mapping on page 567.
• For mapping SIP-to-Q.931 and Q.931-to-SIP release causes, see Configuring
Release Cause Mapping on page 559.