Required Cisco IOS,Cisco Routers freelancer for Cisco Call Manager - Help changing a phone job

I need someone to help with changing a phone extension on an old cisco call manager system.

We swapped the phone but could not get the extension to change. Most probably due to our lack of experience with this system.

I dont expect this to take more than 15 minutes for someone who knows this should resolve it easily.

System information:

OS Description Cisco Internetwork Operating System
Cisco IOS (tm) C2800NM
Cisco IOS Software C2800NM-ADVIPSERVICESK9-M
Software Version 12.3(8)T6 / CME 3.1
Feature Package IP|FIREWALL|VOICE|PLUS|SSH|3DES
GUI Version 1.2

Skills & Expertise Required

Cisco IOS Cisco Routers