So I was trying to follow the guide made by Michaeldaquila in 2017, however when attempting to dial the set "extension" the phone asks for a pin and, when provided, will disconnect the call.
My goal (and yes, I know this is unorthodox, not supported, etc.) is the following:
Allow callers to complete the call (passes call through to desk phone) using number 1
Allow callers to call each of my "departments" (Service = 21#, Billing = 22#, Sales = 23#)
Thank you!