Asterisk Expert Needed

An Asterisk expert is needed. I am needed to to a incoming 7-digit CallerID to 10-digit Translation. My elastix box has 3 POT line coming in from my local telco. When I receive a local incoming call inbound, they pass a 7-digit Called-ID. I need to be able to translate that 7-digit caller-id to the 10 digit caller ID in order to pass it to my other VOIP services when I have my Follow me feature enabled. As the VOIP provider will only accept a 10 digit called id, and if anything less is passed it shows up as anonymous.