Are you sure that the ACK stops at ser? The ACKs should just flow through ser. I have seen a similar problem with XLite where Cisco drops the ACK because XLite there is a bug in XLIte's Via parsing. This is a Cisco gateway appending an x-route-tag to via. Turn on debugging (ALL) on Cisco and check if it drops the ACK due to wrong/no branch info in Via. g-)

Amozurrutia Jesus wrote:

I'm implementing the scenario shown below.

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/ 0 \ ---/ \ | /_\ | ATA1 |---| ____ _ _ _ _ _____ ______/ | / \ / / / / \ / \ |---| FW |---| IP Net |---| CCM | | ____/ _/_/_/_/ _____/ | | | | | | | | --- --- / \ / \ |NAT| |SER| |-T | | | ___/ ___/

When calling between the CCM (Cisco CallManager) and the ATA, SER simply ignores the call ACK. The ACK looks like:

ACK sip:5559853979*sip1.mcm.net.mx=X.X.71.2+17081@X.X.81.92:5063 SIP/2.0 Via: SIP/2.0/UDP X.X.67.218:5060;branch=z9hG4bK29b2c750 From: "5559852600" sip:5559852600@X.X.67.218;tag=16781758 To: sip:5559853979@mcm.net.mx;tag=2602576443 Date: Tue, 30 Nov 2004 23:53:15 GMT Call-ID: fef8ed00-1da1612d-24d-da4334c8@X.X.67.218 Route: sip:5559853979@X.X.81.94;ftag=16781758;lr Max-Forwards: 70 CSeq: 101 ACK Content-Length: 0

The call flow:

CallManager         SIP Server             ATA
     |                   |                   |
     |-- INVITE -------->|                   |
     |<-- trying --------|                   |
     |                   |-- INVITE -------->|
     |                   |<-- Trying --------|
     |                   |<-- Ringing -------|
     |<-- Ringing -------|                   |
     |                   |<-- OK ------------|
     |<-- OK ------------|                   |
     |-- ACK ----------->|                   |
     |                   |<-- OK ------------|
     |<-- OK ------------|                   |
     |-- ACK ----------->|                   |
     |                   |<-- OK ------------|
     |<-- OK ------------|                   |
     |-- ACK ----------->|                   |
     |                   |<-- OK ------------|
     |<-- OK ------------|                   |
     |-- ACK ----------->|                   |
     |                   |<-- OK ------------|
           ......

My guess is that SER does not accept the URI "5559853979*sip1.mcm.net.mx=X.X.71.2+17081@X.X.81.92:5063" because it contains "*+=" signs ore something similar. When calling from ATA - ATA there is no preoblem because ATAs construct the ACK message different (URI and Rote flipped).

Any ideas?

Thanks in advance,

Jesus

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