[another_comment]

I'm not running my own service. I'm using www.iptel.org, they offer a free sip account. Under the hood they use the Kamailio sip server. It is pretty darn reliable for a free service.

Every few months iptel.org goes down for a few hours and I get 408 request timeouts. When Spectrum blocked 5060 UDP, I got 408 request timeouts for a week. It finally dawned on me to try my iptel account on my VPS and my SIP register succeeded. That's when I knew Spectrum had shut 5060 UDP. I tried 5060 TCP and that didn't work either.