I briefly describe my scenario:
CUCM 6.1----->Cisco 2821(voice gtw)--->registered with Sip provider.
Truk between CUCM6.1 and VG is H323, on the VG, I setup a sip-ua (see the VG show-run attached), I also specified on the route pattern the calling party transf.mask to attach the uri on the outbound call. Registration comes up, all I get is called phone ringing, it answers but the call could be eared only in one way: from CCM phone to external phone; not the contrary. When I Call from outside to CCM, The phone Just rings and stop. It doesn't take the call pickup.
VG is connected to the internet with a public IP (no Access list filter for now).
I Already trie the same connection using an UC520 and everything works fine.
I don't know if I have to specify something else on the CCM.
Thank you very much for your help
Ensure that IP routing is enabled on your router. In other words, ensure that your router does not have the no ip routing global configuration command.
Troubleshooting One Way Voice Issues:
Understanding Session Initiation Protocol: