Well that stinks. I just recommended the T46G phones for someone I just built a a system for and couldn’t for the life of me figure out what was going on. It was also my first time using pjsip for everything so I thought I was doing something wrong. In my case, I only had 722, ulaw and 729 enabled. I disabled alaw, but still have the problem.
I have a support ticket with Yealink, but I’m assuming you already went that route.