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New Member

6608 T1 to 3745 problem

My customer wants to bring in voice and modem calls on the same T1 to the WS-X6608 blade and forward the modem calls to a 3745 with a modem bank so as to save on T1 costs.

Call Manager is hairpinning the modem calls out another T1 port on the WS-X6608 to the 3745 with NM-1CT1-CSU using user/network ISDN signalling.

The 3745's physical and ISDN layers come up fine. It even says 'multiple frame established' using various switch protocols.

Although the T1 port on the WS-X6608 gets registered to CM it never gets 'connected'. It always stays in a 'NotConnected' state.

We've tried various configurations for the 6608's T1 port but can never get the port connected. We have 'isdn incoming-voice modem' command on the 3745 as well.

Shouldn't this be able to work? Isn't CM looking for just physical and ISDN layer connectivity just like when it connects to a PBX? Any suggestions??

The funny thing is when we stick a NM-HDV w/ VWIC-MFT module in..It works!! But since it can't terminate data it does me no good.



Re: 6608 T1 to 3745 problem

If the port is showing up as registered on the Call Manager page and is in 'NotConnected' state, then the issue could be that the D channel is not up. Check the configuration of the port such as the framing/switch type etc for the port on the Call Manager. You can also try a T1 loopback plug. With the T1 loopback plug, the port should show up as connected and will rule out any hardware issues with the port.


Re: 6608 T1 to 3745 problem

Do you have one side network (Configured in CM Gateway config) and then user on the 3745 side:

isdn protocol-emulate user

New Member

Re: 6608 T1 to 3745 problem

Who is providing Clocking? When you are on the 6608 gateway page click its hyperlinked IP Address and check its port status.


New Member

Re: 6608 T1 to 3745 problem

I have tried letting one device to accept clocking and then have it provide clocking but it doesn't work. I've also switched the network and user sides with qsig, dms100 and ni1 but no luck.

There is something different about the way the 6608 provides the D channel. A CT1-CSU card should accept an ISDN Voice PRI just fine but in this case there is something it doesn't like about the D channel.


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