Audiocodes: MediaPack 1xx–connected phones cannot call each other

I am configuring Lync 2013 to communicate with AudioCodes MediaPack 118 Enhanced Voice Gateway (the device is not certified for Lync 2013).

Listening port on Lync: TCP 5068

Listening port on Audiocodes: TCP 5060

Audiocodes FXS line 1: 2001

                           line 2: 2002

Lync – Phones traffic flows without problem.

Issue: When I tried to call between phones connected to MP-118 I got a busy signal. Phone call does not pass.

Resolution: In Protocol Configuration – Protocol Definition – SIP General Parameters I had SIP destination port set to 5068 (port on my Lync 2013). It looks like Audiocodes used this port by default for all SIP connection (including connection from connected phone to Audiocodes SIP server itself).

So I added port 5060 to my routing rule describing route for phone-phone calls (switch to  Advanced Parameter list):