I have just experienced a “situation”. I have converted my SIP configuration to PJSIP months ago. There are two registrations to providers, and about 40 extensions.
Everything was working fine until yesterday, when one of the providers experienced problems. Their system was reachable to “ping”, but registrations were not working, so after some time Asterisk gave up on it with Maximum retries reached when attempting outbound registration to ‘sip:10.x.x.x’ with client ‘sip:email@example.com’, stopping registration attempt", so after provider fixed its problems, Asterisk did not register to it until I reloaded the config.
Default value of “max_retries” is 20, which is probably OK for testing, but should be much higher in production. I am not suggesting that you should change the default, but it might be good to add a bit more description here https://wiki.asterisk.org/wiki/display/AST/Asterisk+16+Configuration_res_pjsip_outbound_registration , like to set it to 1000000 (I don’t know if 0 means ‘unlimited’, could not find that in any doc’s, didn’t look at the source)
I have set it to 0 on my Asterisk, and will disconnect one of the providers overnight to test if it will come up in the morning… will report results…