Cannot make external calls from 3103 phone on VCX systems

[scheidel21]

I started a new IT administrator position and inherited a VCX PBX system, of course I have no experience with VCX, and don't find it very intuitive, but I digress. As I am tech support for the system I have nowhere else to go, my phone can't make external calls. I can dial internal extensions till the cows come home, I can receive calls from interal and external callers day and night, but when I try to dial an external number I get a busy signal and my phone says "Temporarily Unavailable" on the display. I have checked and tried changing the profile and calling restrictions, there seems to be no issue with that. I'm just not sure what to look for next. Any ideas or suggestions would be very welcome.