[Asterisk-Users] No communication channel

[Lal, Deepak (Contractor)]

I have following setup:

AnalogPhone_1--TDM400P--Asterisk---SIP---[Softswitch]----POTS-AnalogPhone_2

I can call from AnalogPhone_1 to AnalogPhone_2 and all is fine. 

When I call to AnalogPhone_1 from AnalogPhone_2, AnalogPhone_1 rings BUT 
I hear no ringing tone AND when someone picks up AnalogPhone_1, there is no
"sound" and parties on both end cannot hear each other. Seems that no
communication channel is open!

Any suggestions? Thanks - DL