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T1 CAS connect supervision problem

We just converted a small branch office to IP telephony, and have run into a snag with the LEC. We ordered a DSS (CAS) T1 with 4 channels to be used for inbound DID, as well as outbound calls. We initially thought all was good after placing a few test calls, but soon discovered that any outbound call would drop after 2 minutes 50 seconds.

show voice call summary:


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We never get a connect from the other end, so it times out. Inbound DID calls go to Connect state and are fine.

The LEC says they cannot support E&M wink signalling with their DMS100, at least not without huge effort and cost.They say they are using DID/DOD wink signalling with DT Digitone which doesn't tell me much. I did research it enough to find out that digitone is simply Nortelspeak for DTMF, so we are good there. They cannot explain to me what DID/DOD wink means in terms of ABCD robbed bit signalling so I am stuck. I sent them a Cisco doc on IOS CAS, and they were amazed that Cisco supports only FX and E&M. They just keep tellimg me I need to turn on DID, and it will work.

Two questions:

1. Where is the timer that is dropping the call? We are running MGCP with a Call Manager 3.3.3SR4A to a 3745 with 12.3.4T. Setting the timer to allow for a long call would help, until we find a solution.

2. Can anyone offer clues as to interfacing CCM with DMS100 DID/DOD DT wink?

New Member

Re: T1 CAS connect supervision problem

I would start by asking the LEC if there is a remote shelf Parigan in the picture. I have worked with a lot of remote office locations that the local LEC would have a central office DMS-50,100,250 with a lot of remote shelf units. Then they would setup a parigan to supply tone way outside of the specs. This is where the rub comes in......

Amost of the remote units have to use DID to translate to the remote shelf. This is where the "Extended Shelf" and "Shelf" back to the Switch figure out if a call is on-hook or off-hook. Sounds like the DMS supports what you need. Just the remote shelf or extension shelf can not.

Just a guess.....If you call in from a out side line like a cell or second line and let the station ring one time, hang up the cell phone the call keeps ringing? Just another issues of a remote shelf or repeater. Another question is do your out bound calls die every time or just some times?


New Member

Re: T1 CAS connect supervision problem

I am having the same problem with a 3745 connected to a Nortel 61C when dial across the T1 to the Nortel and out the PSTN we never recieve offhook signal from the Nortel. Audio cuts through but the Nortel will timeout and drop the Call. We recieve the connect when dialed from the PSTN to the Nortel then routed to the Cisco Gateway.

Did you ever find a solution for this?

The Timer setting ?

Thanks in Advance

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