I am trying to integrate CUCM 6.0 with nortel via sip trunk. When i dial to nortel extension, it rings but the moment nortel phone is picked, call gets disconnected.
I am using g.711 alaw and having same codec on nortel side also. Also i am using MTP available with CUCM itself.
My Nortel epabx is behind firewall and all the ports between Nortel and CUCM are open over ip.
CAn Anyone help me that what can be the issue.