Specifications

Spectralink 84-Series with AudioCodes Gateway and Avaya Communication Manager: Interoperability Guide

1725-86914-000_C.docx

September 2013 57

Avoiding a Routing Loop

In the last section, we told the Mediant Gateway to route all calls that are not found registered to

the SAS to the PRI and on to the PBX. This keeps our routing rules in the Mediant Gateway

relatively simple, and allows almost all of our dialplan and routing rules to be maintained on the

PBX. However, we must tell the Mediant Gateway what to do if it receives a call from the PBX

intended for a station that is not found to be currently registered to the SAS. This could occur if

an extension defined on the PBX as part of a block that “belongs” to the Mediant Gateway (see

section 6 of Chapter 8) is sent to the Mediant Gateway and is not found to be currently

registered, or if that station was simply never built, but happens to reside within the range of

extensions defined on the PBX to be sent out to the Mediant Gateway . If we do not perform this

step, the Mediant Gateway would send a call to an unregistered station back to the PBX. The

PBX would check its rules and send these calls back to the Mediant Gateway . This could go on

for some time. In our testing this “routing loop” eventually resolved itself without eating up all of

the bearer channels on the PRI, and the calling party was presented with a re-order tone.

However, we can make more efficient use of our resources and provide callers with a better

indicator of what has happened.

Options for handling such calls could include routing them to a vacant extension to a recorded

announcement back on the PBX telling callers that they have dialed a number that is currently

unavailable. Or you could have them ring to a desk station somewhere. Alternatively you could

route them to a non-existent number on the PBX and callers would simply be given a re-order

tone.

1 Navigate to VOIP->GW and IP to IP->Manipulations -> Dest Number IP->Tel

2 Add a Destination Index for each unique block of extensions you have defined on the

Mediant Gateway (in our example we have only one: 70xx).

3 Configure:

Destination Prefix

This is the block of numbers you are sending to the Mediant

Gateway followed by a # sign. Note that the Mediant Gateway will

not look at this table to route these calls unless it has already

checked the SAS proxy and determined that the phone is currently

unregistered. (In our example we used 70xx#)

Source Prefix

Source IP Address

Stripped Digits From Left

Enter the extension’s length. (We stripped all four digits in our

example)

Stripped Digits From Right

Prefix to Add

Enter the extension number you wish the call to re-route to: For our

testing purposes we pointed them to a CCMS station (x-3044)

residing on the PBX.

4 The remaining fields should stay at the default value.