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RAS callback cancels on certain modems

I have a PRI on a 3660 for RAS. Call back works perfectly for my modem (Xircom), but an on-board modem on an IBM laptop does not work.

The router calls back to the IBM which answers the call only to have it dropped by the router almost immediately. I suspect that the router's modem trains in to the IBM when it dials, but the IBM does not train in to the router when it dials back. Am I correct? If so, is there a work-around, or what is the problem?


Cisco Employee

Re: RAS callback cancels on certain modems

We need to know the modem firmware versions that you have on mica modems on 3660 and on ibm's laptop modem along with modem type..

Pl. make sure you have atleast firmware on mica modems on 3660 along with the recommended modemcap as located at

Now on IBM laptop, do you hear the trainup sound when the router calls back?

Pl. turn on following debug on router and post it for a call.

debug ppp negotiation

debug modem

debug modem csm

debug ppp cbcp

debug callback

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