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Modem relay issue between two H.323 Voice Gateways

Hi all,

I have the following situation:

There are 2 locations, A and B, each having a Cisco 2851 Voice Gateway, interconnected via a MPLS VPN Provider. Each Voice Gateway is an H.323 Gateway, and has POTS and VoIP dial peers.

For modem relay configuration, I have the following:


voice service voip


    call start slow

  modem relay nse codec g711alaw gw-controlled


I have the following issue when dialing for a modem call:

For a call from A to B results a modem relay connection, but for a call from B to A the resulted connection is not modem relay, and it drops the call.

The configurations from both A and B Voice Gateways are approximately identical. Both Voice Gateways are connected to a Cisco Unified Call Manager.

Each A and B Voice Gateway has a EVM-HD-8FXS/DID module and an PVDM2-48.

Any help on this issue is welcome.

Thank you in advance.


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