3CX Upgrade: 408 Error

[Baphijmm]

Recently upgraded to 3CX 14, which unfortunately meant getting new phones (the old ones we had aren't supported); trying to get everything set up, but for some reason, any calls made to the IP phones do not properly connect. The dialed phone rings, and the calling phone also hears a ring tone; however, upon picking up the ringing phone, it reports "Answering" but never succeeds in doing so. Looking at the logs, the call 100% fails with "Cause: 408 Request Timeout/INVITE from local" as the reason. This has been tested with the same results across both Cisco SPA502G (upgraded to both the most recent 7.6.1 and the recommended 7.5.5 firmwares) and the iPhone 3CXPhone. Because the call never registers as "Answered", the phone rings a second time after ~30 seconds, even if the call has been disconnected.

Calls from the exact same internal IP phones to external numbers (i.e., any number not on our network, that has to go through our SIP provider CallCentric) work perfectly; zero issues with calls coming *from* these phones, but any calls going *to* any phone registered with the PBX fail to answer correctly.

Any idea what I might be doing incorrectly?

 

[lneblett]

Look at any firewall that may be installed and active on the machine upon which 3CX resides and disable it as a test. If this results in success, then you can leave it disabled (if certain it is not exposed to other threats) or:

External RTP ports are different than those used for the Internal ports and it sounds like the firewall on the machine may be getting in the way. You can look at the ports in the Network section of 3CX and then make certain that for any realm (public, private and domain) that the ports are allowed.

 

[Baphijmm]

All firewalls on the machine are already disabled; we have a separate appliance for that. All of these faults are occurring without going through any firewall.

 

[Baphijmm]

Figured it out on my own; this is a pretty serious bug with 3CX, apparently.

PBX computer was set up with two IP addresses, two separate subnets within our network. The calls were being rung to the correct subnet, but then were actually trying to connect through the incorrect subnet. 3CX was configured to only use the one (correct) subnet; the other subnet is there for legacy systems on our network, and really wasn't necessary on that machine, so removing it wasn't a big deal. That being said, a PBX system misbehaving in such a way on a machine with multiple IP addresses, especially when the software supposedly has provisions for that, is pretty problematic.