SIP DIDs All Ring Busy

[Drew9213]

I have a SIP trunk set up with 3 SIP DIDs associated with it. When first created all 3 DIDs would ring in correctly when called, however, I've noticed that after a period of time (roughly 30 minutes) calls to any of those DIDs result in dead air for 5-6 seconds and then give a busy tone. Running a wire capture on it I see a 600 Busy Everywhere code. What's strange is that if this is happening I can pick up a phone and dial out of the phone system and after doing this all incoming calls immediately start ringing in correctly again. Then roughly 30 minutes later they start ringing busy again and I have to dial out before incoming calls will ring in correctly. I've worked with the SIP provider and they are insisting that the issue is not on their side..... 3CX Version 15 by the way.

 

[Drew9213]

An update on this is that now when the lines are ringing busy and I dial out and get it back to being able to ring in, if no calls are active for roughly 10 minutes, it goes back to ringing busy.

 

[briankayser]

Are you going through a firewall to reach your SIP provider?
It sounds like a potential timeout issue on your firewall where it is closing down established ports.

Disable any SIP Fixup or ALG if you are. I'm assuming you have a static public IP.

 

[Drew9213]

It is going through a firewall, a Cisco ASA 5506. I have verified that all of the needed ports are open and that SIP ALG and SIP inspection are turned off.

 

[leejor]

Does the 3CX activity log give any clues as to what is happening? I assume that the set(s) show as registered and available.

 

[briankayser]

That's practically the same firewall that I use.
I'm assuming you have static IP and are doing one-2-one NAT and no PAT??
Perhaps Google the ASA's IOS version number for any known SIP issues with that release.

Do you have an alternate/test SIP provider you can test with?

 

[Drew9213]

I am doing one-2-one NAT. I just disabled all inspection rules to take the giant hammer approach and so far I have not had the issue happen again. Now for the long process of adding back inspection rules one by one. My initial guess here before going through that whole process is that while SIP ALG was disabled, SIP inspection probably wasn't as we usually leave this enabled for all of our installs. Why it would suddenly cause an issue now I have no idea. Will update once I get all the rules back in and figure out exactly which one it was.