Modem call over Voip link

[TraianosTraianos]

I have two BCM 400's connected by a Voip link with one of the BCM'S having an ISDN link for incoming and outgoing traffic. My problem is that when I call from a modem, via an ATA from the BCM without the ISDN the call goes across the VOIP link and out of the IDSN but will not connect, it starts to train as per normal but just hangs. I have tried forcing the modems at 9600 but still no go. If I make a call from the BCM with the ISDN link, so as to eliminate the VOIP link all works ok. I have put a secondary qsig link in between the two BCM'S and tried the modem call over this link and still expierence the same problems.

 

[biv343]

Only type of data transmission via modem that is supported over VOIP trunks is T.38 fax. Regular modems won't work. Ran across this quite a few years ago with the 9150 product and ATA's in the back of phones.

 

[TraianosTraianos]

Thanks for your reply, but what about the Qsig link as I have the same problems via this link?

 

[biv343]

Pardon me for not knowing what your QSIG link is - I'm assuming that is the same as a MCDN/SL1 private T-1 link here in the US.

If that's the case, and it is indeed a private T1/E1 circuit, check your clocking and make sure that is set correctly. Clocking problems will cause modem and ATA issues.

 

[TraianosTraianos]

Yes you are correct the QSIG is the same as a MCDN/SL1 link.
I will check the clocking but this is how it is currently set, on the BCM with the ISDN and Qsig link I have the ISDN set to Master and the Qsig set to secondary and on the remote BCM I have the Qsig set to primary.
I wondered if this was wrong and planned to change the Qsig on the remote BCM to secondary and the Qsig on the BCM with the ISDN link to primary this morning.