Incoming fax2extension rings busy/error

[benf]

I have two 3cx systems we recently noticed that we have several fax DID's and on both systems one or two of them do not work. I get an error from the carrier side basically the line is not answering. If i flip it to an extension and dial it right back it works and the phone rings. On both systems I have multiple inbound fax DID's and some of them work and some have this issue. It was all working when we setup and installed in the last few months. All 15.5 and latest updates.

Anyone have any idea? Ive gone back and forth on checking all the settings, I mean there isnt much obviously.

 

[lneblett]

A little more detail is needed. Are these all going to fax extensions with ATAs or to the inbuilt fax server?

Have you done a capture? This may show that the call is being answered, but having an issue flipping to t.38 or g711 and/or the Internet is not stable enough.

Your post subject line indicated rings busy, but the body indicated no answer. Not sure which is correct, but the capture should shed some light.

 

[benf]

Hi, sorry it rings fast busy on my end, and I get a trunk error from the SIP provider. Im using the built in fax2email extension option. We have 6 fax lines overall, and 3 of them do not work and 3 seem to work okay. I turned up logging and dialed the numbers and its like they dont even make it. Im getting 480 temporarily unavailable

 

[YiannisH_3CX]

Hello @benf

Do you see the calls actually hitting the PBX? The best option in this scenario is to run a wireshark capture along with verbose logging and see it the calls are reaching the PBX. IF they do who is sending the cancel message? If not then you should contact your provider for more info. Are all the DIDs from the same provider?

 

[benf]

So I pulled up wireshark , this is a non-production system right now (we are porting). I called it and I got a SIp/SDP 937 Request: INVITE: sip:CID@PBXIP:5060 . I switch the inbound DID to an extension and I get the same SIP/SDP 937 Request, except the call picks up on the extension. I do see a few packets later a 430 Status: 404 Not Found on the FAX call, but the voice call goes to a SIP/RTP stream. Keep in mind this is happening on two different systems with different numbers, but some of the numbers work. All of the DIDs are the same vendor.

 

[YiannisH_3CX]

I would recommend running a capture on a working attempt and a non working and comparing the two to see what is different. You will need to expand the Invite messages to get more details.