I have a customer with a SIP PRI from Optimum (Cablevision).

It works fine except if you are on the phone for 45 minutes or more. The boss makes long phone calls and after that time she no longer can hear the other party. The far end does in fact still hear. They hang up and call each other back and confirm.

System is a Nortel Norstar. I've never had this problem with a Nortel. But this no speech leads me to believe this is a SIP / PRI issue.

I've opened a ticket with Cablevision who don't have an answer..yet.

Any thoughts?

Good luck. Unless you can actually see the channel data on the PRI when this happens, you can't really tell the LEC what the problem is. I went around and around with the LEC on just this exact same issue, except it was a straight PRI. LEC technician after LEC technician "tested good." It didn't get fixed until I left my Fireberd on the system and captured the channel data that proved there was a framing loss on the carrier end that caused one way transmission.

The problem is, at least here, anyway, the LEC technicians are spread so thin and given 15 jobs a day to complete, they just don't have the time to babysit a circuit and wait for something to happen. Add to the work is a mix of 23 or 24 channels that the problem "can" be and, well, you see the complications.

One thing you might have the customer do. Ask them to keep a log and record date, time and, if possible, which channel the call was on when the failure occurred. You might also include if the call was inbound or outbound and what number was called or was calling into the system. You may find the problem is only on one or two channels. This would give a knowledgeable technician a good clue as to what needs to be done.

Also, don't think it's not a telephone system issue. I had one system with a similar issue and it turned out to be a bad station module. The standard method of troubleshooting is replace or swap trunk/station modules or anything between the demark and the station, including the station. If the problem persists, it has to be a LEC issue.

Rcaman

Google "One way transmission on SIP problems" CISCO has some good info. Its mostly routing and translations issues if I understand it correctly.

we were advised by the telco to reboot the modem and the SIP PRI device (edgewater). we'll see.

SiP is still voip...and long calls can suffer from packet confusion and have a greater chance of fading or dropping altogether. It is just the way it is.

What kind of circuit? You may have a SIP Trunk to a IAD and a PRI hand off to the Nortel. So you incur one way audio after X amount of times. You're going to want to look into the network. There is no such thing as packet confusion.. they arent human. Your best bet is to run a packet capture on the line and see if you can catch the call when it goes no audio..

I just noticed you have an edgewater. If you ssh/telnet into this you can run etherreal captures right from it.

Have you timed it yourself? Is it exactly at 45 minutes? If then soumds like a timer