NS700 Spectrum/Charter SIP disconnect at exactly 15 minutes

[Wisco33]

I have a customer with Charter SIP Trunks and a Panasonic NS700. At 15 minutes exactly, the user is unable to hear the other party, but the other party can hear them. BTS believes it to be either a carrier or firewall issue and the carrier believes it to be PBX or Firewall. Charter's SIP Gateway device is installed on the customer's LAN and was provisioned with a local IP address, so I'm not sure that the firewall is even in play? Charter's SIP Gateway must go out via their own coax/fiber, and strictly communicating with the PBX through the LAN switch- but somebody correct me if I am wrong.

We had another customer call who had come to us from a different vendor and they were having the same issue, but with a TDA50. They were looking for a quick fix as they were a small branch of a larger corporation that was soon going to move onto corporate's VOIP system out of state, so we were never able to resolve it with them.

I have to imagine that SOMEONE has gone through this and may be able to let me know what the fix was? Was it Charter/Spectrum? Or PBX? Or some common firewall setting?

The IT guy had been working with Spectrum/Charter up until this point regarding this issue and sent me the following response from Spectrum/Charter:
*** "Traced the call and found that the call is being ended from the customer's direction. This call initially sets up for out of band signaling. At the 15 minute mark when the session timer is invoked from the Voice core, the re-invite still is offering oob signaling.
The customer's PBX answers with a 200ok requesting in-band signaling, The voice core, re-invites with in-band signaling in SDP as requested, phone system 200oks, voice core Acks, then customer side sends the sip BYE message.***

Please let me know if anybody has any information!


Thank you!

 

[obtsystems]

Do you have a sonicwall firewall?

 

[Tele-tech]

Check the firewall/router for a setting called UDP timeout, generally set up in seconds. I've had this before cut off phone calls.

I also had a bad router once do this exact thing, a Cisco RV320. Took a long time troubleshooting with Wireshark to determine where the issue was, since it took time to duplicate.

 

[RNA Errors]

I too have had this issue with Charter. The last ticket I opened two weeks ago resulted in them making a change on their gateway. They will not tell me exactly what was changed nor give me any PBX configuration changes to make from what we have already. Not sure if it helped yet HOWEVER here is the issue: PBX not responding to SIP-REINVITE.

"Our voice engineer investigated and found that at the 15 minute mark, a re-invite was sent to your PBX to keep the call connected.
We did not get a response from your PBX to this re-invite.
We did receive a 'trying' response but nothing else for 30 secs.
Our engineer made a change on the gateway to try and help get a response from your PBX."

I hope this helps you, let me know if you solved your issue or not.

 

[RNA Errors]

obtsystemsprogrammer: Why did you ask about Sonicwall? We have one with the gateway and PBX hanging off of a switch outside the Sonicwall (so it should just be the switch involved in this given they are both on the same VLAN) however for future reference it would be nice to hear your reason.

Thank you

 

[obtsystems]

There is a udp timer on the sonicwall that needs to be extended for unsupervised udp traffic that is set to 15 minute’s that will end the call.

How can the switch be outside the firewall? How are you getting internet

 

[RNA Errors]

Spectrum's voice gateway is a separate line of service to the Internet which has its eth0 port connected to a core switch on the voice vlan as is the PBX. I'd extended the UDP timer earlier in this ordeal before it occurred to me that the gateway is actually the core switch. For future reference though I wanted to make sure I was on the right track given that this is an atypical configuration and no doubt I will see a similar issue when transiting through a firewall. Thankyou!