Asterisk 18 / pjsip / FreePBX 15.0.17.24 sends 180 ringing to trunk on inbound calls even before the outgoing invite is sent to the internal device.
The routing is pretty trivial:
Trunk -> Inbound route (“Ringing” switch is not enabled, no inband_progress and no rpid_immediate) -> extension
At the moment, two ringings are sent to the provider: the first ringing, condition less directly after the trying, the second is the one received from extension and forwarded to trunk. Or it is Ringing -> 486 busy, if the extension is busy.
Is there any way to prevent the condition less first ringing?
Ok - I’m answering myself. It’s the “r” in the dial options (of the extension or the global one in the advanced settings. Removing it makes it work as expected.
Be aware that some trunking providers will treat the absence of (at least) 180 or 183 as ‘no response’ for initiating a failover action, even though your system sent a 100 Trying.
For example, if the failover timeout is 5 seconds (set by you on their portal, or fixed by them), then if there is no response (other than 100) to an incoming INVITE for 5 seconds, they will cancel the call and send it to your specified failover destination (mobile phone, voicemail, backup PBX, etc.)
Good point! But shouldn’t this be the expected behavior? 5 seconds w/o any 180/183 is a clear sign for me, that there is something seriously broken which should be repaired urgently.