When an originating phone switch sends out a phone number as caller ID, the telephone company receiving the call is responsible for looking up the name of the subscriber in a database. Additionally, nothing ensures that the number sent by a switch is the actual number where the call originated.
If the PBX would send out the "calling party name" it would be the responsibility of destination CO to replace that piece of IE with the information contained in their database.
Kyle Holladay
ACA-I, ACA Call Center, ACS-I, ACS-M, TIA-CTP, MCP/MCTS Exchange 2007
ACE Implement: IP Office
"If it worked the way it should you wouldn't need me