AudioCodes Mediant 800B User Manual page 384

The device searches for an alternative IP destination when any of the following connectivity
states are detected with the IP destination of the initial Tel-to-IP routing rule:

No response received from SIP OPTIONS messages. This depends on the chosen
method for checking IP connectivity.

Poor QoS according to the configured thresholds for packet loss and delay.

Unresolved DNS, if the configured IP destination is a domain name (or FQDN). If the
domain name is resolved into two IP addresses, the timeout for INVITE re-
transmissions can be configured using the HotSwapRtx parameter. For example, if
you set this parameter to 3, the device attempts up to three times to route the call to
the first IP address and if unsuccessful, it attempts up to three times to re-route it to
the second resolved IP address.
The connectivity status of the IP destination is displayed in the 'Status' column of the
Outbound IP Routing table per routing rule. If it displays a status other than "ok", then the
device considers the IP destination as unavailable and attempts to re-route the call to an
alternative destination. For more information on the IP connectivity methods and on
viewing IP connectivity status, see ''IP Destinations Connectivity Feature'' on page 382.
The table below shows an example of alternative routing where the device uses an
available alternative routing rule in the Outbound IP Routing table to re-route the initial Tel-
to-IP call.
Table 24-4: Alternative Routing based on IP Connectivity Example
Main Route
Alternative Route #1
Alternative Route #2
The steps for configuring alternative Tel-to-IP routing based on IP connectivity are
summarized below.

To configure alternative Tel-to-IP routing based on IP connectivity:
1. In the Outbound IP Routing table, add alternative Tel-to-IP routing rules for specific
calls.
2. In the Routing General Parameters page (Configuration tab > VoIP menu > GW and
IP to IP > Routing > General Parameters), do the following:
a. Enable alternative routing based on IP connectivity, by setting the 'Enable Alt
Routing Tel to IP AltRouting' (Tel2IPEnable) parameter to Enable.
b. Configure the IP connectivity reason for triggering alternative routing, by setting
the 'Alt Routing Tel to IP Mode' parameter (AltRoutingTel2IPMode) to one of the
following:
♦
♦
♦
c. The device plays a tone to the Tel endpoint (for analog interfaces) whenever an
alternative route is used. This tone is played for a user-defined time configured by
the 'Alternative Routing Tone Duration' parameter.
User's Manual
Destination
IP Destination
Phone Prefix
40 10.33.45.68
40 10.33.45.70
40 10.33.45.72
SIP OPTIONS failure
Poor QoS
SIP OPTIONS failure, poor QoS, or unresolved DNS
Mediant 800B Gateway and E-SBC
IP Connectivity
Status
"No Connectivity"
"QoS Low"
"ok"
384
Rule Used?
No
No
Yes
Document #: LTRT-10278