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New Member

Issue with serial interface

We have 4 T1 PRI's coming into our router.  I've had complaints on the floor that random people get dropped calls, or where the other end can't hear them, and dial tones everytime they talk.  I've called my own number numerous times and noticed that it's only on a specific interface out of the 4.  I don't see any errors, collisions, interface resets, or runts.  The interface looks clean.  How am I to prove this indeed is an issue with this interface?  The only thing I can think of is that that interface is going bad.  Any thoughts?

New Member

Please post the output from

Please post the output from the following debug for any test calls:

debug isdn q931

Also please refer to this document:

It might also be prudent to consider cabling issues; such as termination to the card and termination to the network.

VIP Purple

Hi Ninja, You can also try

Hi Ninja,


You can also try shutting down the suspected Controller T1 port and observe.


Further, you can also try swapping the working PRI with suspected T1 port or T1 PRI.