We have a new conference phone for one of our meeting rooms, and it’s a different brand than what we had before (a Vtech VCS, replacing a Konftel). I cannot get the new phone to register, no matter what I do. (I set it up first in FreePBX endpoint manager, and when that didn’t work I tried hard coding the server info directly on the phone). The extension worked with the previous phone (and a different test Aastra phone I grabbed from a desk), and I tried both the correct and a new extension with the new phone; neither worked.
The phone is definitely getting an IP in the correct range from DHCP, and is on the correct VLAN, etc… I can go to the phone’s web UI, so it’s reachable. But nothing I put on either end will make this phone talk to my server for some reason.
I’ve tried turning on sip debug, and searching the logs for the extension, and I’m not seeing any entries. The phone log shows it booting, trying (and failing, since that line doesn’t have an internet connection) to check for updated firmware, but nothing about registration attempts. 
I’m not sure how else to troubleshoot this, without error messages to go on or anything useful. Anyone have any thoughts about where else I could look?
Working now.