Fax and modems can't call out, no handshake

[Supermanfan]

Hello all, I've been working on this trouble for a few months now and I just can't seem to come up with an answer.

We upgraded our switch to a CS1000. We were using the old trunks from the old switch to make our outbound calls and everything worked fine. Once we ported our numbers to the new SIP circuit, we have not been able to Send faxes out or connect with modems. When we were still using the old trunks, we had no problems. The SIP carrier is adamant the problem is on our end, but it worked properly through normal T1/PRI's. I can receive faxes and can make faxes both ways over our tie lines. Its only faxing outbound.

Things I've checked:
-Baud rate on the faxes
-CODEC
-Class of service
-NCOS

I traced calls on multipole switches to compare the routes of the calls and everything looks good. Anyone have any ideas or seen this? One thing I keep reading on here is that the SIP circuits seem to be garbage.

EDIT: The faxes make the call and the other side answers, but I get "Communication error, fax could not be completed" on both ends. Same thing with the modems, the call answers and starts talking to each other, but them gets stuck and doesn't complete.

Thank you!

 

[Firebird Scrambler]

T 38 springs to mind here. Is it enabled. I will say that getting faxes to work over SIP trunks is very much a hit & miss thing. I always try to get customers to stick with traditional lines.

Firebird Scrambler

Nortel & Avaya Meridian 1 / Succession & BCM / Norstar Programmer

Website =

http://somertel.myfreesites.net

linkedin

 

[Supermanfan]

Firebird Scrambler,

Yes I have T.38 enabled. WE have multiple sites/switches we handle, When I send faxes out of other switch's wit PRI's, my trace reports that the media profile: CODEC G.711 MU-LAW PAYLOAD 20MS VAD OFF

This is the trace in the switch with the SIP circuit. media profile: CODEC T.38 NO-LAW PAYLOAD 1MS VAD OFF. that's what I was told to do. Thoughts?

 

[KCFLHRC]

Maybe I missed it but how are the SIP Trunks connected to the CS1K. Do you have a signal server for the SIP trunks with some type of SBC or what?

 

[Wanebo]

Are you using AT&T for your SIP trunks? They are notorius for not playing well on fax and modem connections. We worked with them for over 6 months at one site to try to get it straightened out and ended up throwing in the towel and installing some additional trunks in from a different vendor. Besides fax over SIP working just fine over these new trunks this also gave us some diversity in routing in case the AT&T trunks went down or there were routing issues in the step-Ma Bell network.

 

[Supermanfan]

KCLHRC: Yes, the SIP circuit is provided by the vendor Fusion, and it is a Verizon circuit. Its built in the PBX as PRI's because Fusion told us that once it leaves their server, its a T1. That's how it was explained to me.

Wanebo: So Fusion is the vendor who manages the circuit, and the carrier is Verizon. I was told on here about a number to call that tells you who you long distance provider is. 700-555-1414 for out of state long distance, or XXX-700-4141 (XXX being your area code). If I call the number is says AT&T is my provider.

 

[KCFLHRC]

So to the Nortel PBX this isn't SIP, it's a PRI? What Fusion told you makes no sense to me.

 

[LoPath]

Sounds like they're just handing it off as a PRI. So rather than a straight Ethernet handoff, they convert it to a PRI. Pretty common to allow folks to interface with legacy PBX equipment if they don't have or can't afford a SBC.

@Supermanfan: As far as that 700# is concerned... don't get wrapped around the axle about your results there. The choice of long distance provider is a totally separate thing than the service provider. Example: You can have local phone service from Windstream but tell them you want AT&T for long distance. That's what that 700# is going to tell you.

LoPath
Maintain HiPath 4000 V5 & V6, OpenScape Xpert V4 & V6, OpenScape Xpressions V7, OpenScape Contact Center V8, OpenScape Voice V9