I am using Cisco Unity Call Manager 5.1 (3),and the Voice gateway is Cisco2821,and I have 200 IP 7940 G phones nad the PSTN is terminated to cisco 2821 router where the same E1 PRI is also terminated.
Now the problem is from any IP phone to IP phone it is working fine,but when I make a call from IP phone to PSTN phone,the call is landing and the PSTN user pick up call and He/She is able to listen the voice,but the IP phone user is not able to listen the voice.
What could be the problem? I am new to IP telephone.
I have to solve this escalation.
I do not have the configuration.
Thanks and Regards,