I have an Option 81C rls. 3 connected to an Avaya GR3 via a T-1 programmed as Tie lines (not DID). My 81C is going to 7 digit dialing the Avaya is not. What are my options for the Avaya? Right now they dial 3XXX and the calls are routed to the Option 81C telephones. When I go to 7 digit dialing the new numbers on the telephones would be NXX-3XXX. I am looking for the best low risk way to do this. I am dealing with two different vendors.