Flowroute - Calls from single number not connecting

[shaquille_oatmeal]

We have been running 3CX in Azure for the past few years. The customer has been operational with no issues. Recently, they have a client that is reporting that whenever they attempt to call, the phone call hesitates to connect for a period of time, then says "Incompatible, and places alternating tones. We've made no configuration changes (aside from add/remove extensions as people have come/gone) since we've set this up.

What's interesting, this behavior only comes from a single phone number. I can see the call come in to our SIP trunk provider (FlowRoute). FlowRoute sees the call route to 3CX, but 3CX rejects. Here is their response:

When we look over the call example provided, we're seeing a 407 Proxy Authentication error come back from your 3CX system at xx.xx.xx.xx:5060. As for why, typically, this error is thrown when there's something wrong with the inbound dial pattern with 3CX, but it would be happening with all calls, not just a certain number. However, considering this happening with a specific number, this may be something you'll want to reach out to 3CX about to have them investigate further as they are the manufacturer of the phone system and would have better tools in aiding in why this is happening. Thank you!

Here is what FlowRoute's call log shows (Time are off by 5 hours, sorry):



3CX doesn't even register it on their end:



Our Inbound DID config (which is what FlowRoute suggested I look at):



What gives??? Every other call places just fine... Looks like the originating provider makes it to FlowRoute, and according to FlowRoute 3CX is rejecting the call... Any ideas?

Cheers,
HG

 

[leejor]

I would look at the 3CX Activity Log (Verbose setting), as that will show the SIP messaging between 3CX and your provider. Compare a working call, to the number not working. My first suspicion, the dialed number being correctly sent, is something at the terminating end. I assume that the number is reachable from other phones.

 

[YiannisH_3CX]

If the PBX replies with a 407 that means that you are running into source identification issues but that would mean that the called number is different and not the callers number which is strange.
Since this is happening from a single phone number then you should use the activity log as @leejor suggested to see what is different with this call.
Since the call was rejected with a 407 authentication error you will not see it in the call log as it did not make it into the PBX so that is normal.