Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
New Member

strange call delay problem

We are connecting a 3662 to an Avaya PBX. IP phone(7610) can call the Avaya extention phones and the outside PSTN phones thru the PBX well, but with one strange problem.

When we call the outside PSTN phones thru the PBX, the IP phone needs about 4-5 seconds to be ready to send voice to the other side. However, from the ip phone we can hear the pstn phone immediately. This is reflected by the display on the ip phone. After we can hear the other side's voice for 4-5 seconds, the ip phone shows "00" on its screen and starts counting call duration.

Often this causes the person at the receiving PSTN phones to doubt that the call is a technical failure as he/she hears nothing, so he/she puts the phone on hook again.

We use E1 cable to connect the PBX and 3662. Signaling is E1/R2 or E1/E&M(this symptom occurs for both signaling method but now we are using E1/E&M). The signaling between AVAYA PBX to the PSTN is E1/R2 DID for incoming calls and E&M for outgoing calls.

Anybody knows why or how to solve this?


Re: strange call delay problem

Often times complex troubleshooting issues are best addressed in an interactive session with one of our trained technical assistance engineers. While other forum users may be able to help, it’s often difficult to do so for this type of issue.

To utilize the resources at our Technical Assistance Center, please visit and to open a case with one of our TAC engineers, visit

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

CreatePlease to create content