I’ve been having a lot of issues with older Yealink phones not working with pjsip and TLS. Keep getting busy, and end up setting taking the lazy road (and less secure), and setting old broken endpoints to use UDP instead. You can also downgrade the extension to SIP and sometimes TLS will work, but moving it to PJSIP just breaks it. For security sake, please set your phones behind a VPN if you’re going to register without TLS. I happen to be spending more time at the office lately and wanted to take my spare T46s up there to use, since I was on a Polycom VVX 310 or something (I can’t stand Polycom, I dont know why). When I happen to move my T46s over from home to the office, I had some free time and decided to fix it.