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

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

ISDN PRI Callback not initializing

Hardware use : Cisco 3620

Line : ISDN PRI 30 channel

ISDN PRI 30 channel calls are not calling back, It is just prompting at the user site as "Waiting for callback" and after some time desconnected...

I checked with the normal dialup without callback it it is working fine with 64k ISDN as well as 56k analog modems.

I checked the callback with the same ISDN 64k Dialup as well as Analog 56k Dialup, for both it is rejecting... hope I didn't miss any configuration... I already got through with cisco documentation and It simes the configuration if fine... I Checked with the TELCO guys and there said no restructions from there side about our PRI 30 channel line, we can make any local calls without any problem...

Any help will be highly appriciated...



Re: ISDN PRI Callback not initializing

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 login to create content