AudioCodes Mediant 500 E-SBC, User Manual

Page: 405 / 920

User's Manual 24. Routing
Version 6.8 405 Mediant 500 E-SBC
24.6 Alternative Routing for IP-to-Tel Calls
The device supports alternative IP-to-Tel call routing, as described in this section.
24.6.1 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 Inbound IP 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 Inbound IP Routing table, see ''Configuring Inbound
IP Routing Table'' on page
394.
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 Inbound IP Routing table.

Phone number is not located in the Inbound IP Routing table.
This default release code is set to Cause Code No. 3 (No Route to Destination).You can
change the code number using the 'Default Release Cause' parameter, located on the
Advanced Parameters page (
Configuration tab > VoIP menu > SIP Definitions >
Advanced Parameters ).
Notes:
•
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 mapping SIP-to-Q.931 and Q.931-to-SIP release causes, see Configuring
Release Cause Mapping on page
378 .
The following procedure describes how to configure alternative routing reasons for IP-to-
Tel calls in the Web interface. You can also configure alternative routing reasons for IP-to-
Tel calls using the table ini file parameter, AltRouteCauseIP2Tel or CLI command,
configure voip/gw routing alt-route-cause-ip2tel.

To configure alternative Trunk Group routing based on Q.931 cause codes:
1. In the Proxy & Registration page, set the 'Redundant Routing Mode' parameter to
Routing Table so that the device uses the Inbound IP Routing table for alternative
routing.
2. In the Inbound IP Routing table, configure alternative routing rules with the same call
matching characteristics, but with different Trunk Group destinations.