Friday, May 04, 2012

Call forward from Elastix to PSTN via SIP trunk fails

This article applies to Elastix 2.0.0-36.

In Elastix, we might see failed call forward (CF) if the call path is:

PSTN-->Elastix-->Call Forward->SIP trunk->PSTN

The reason is that most SIP trunk providers routes call only if the call
is from a registered caller. In the case above, the caller is indeed
the outside party and therefore CF fails.

To circumvent this problem, we should configure SIP trunk as below.

Outbound Caller ID: <a valid CID for this trunk>
CID Options: Block Foreign CIDs

That instructs Elastix to send the trunk CID instead of foreign CID.
CID defined for user/extensions are transmitted.


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