This paper mainly introduce a protection scheme using wireless commercial terminals to guarantee voice communications for enterprise customer with private line of voice service which encounter certain conditions

such as the service is interrupted by serious transportation interruption or customer equipment breakdown that can not be repaired in a short time.This scheme ensures customers originate and terminate calls as normal using wireless commercial terminals.The outgoing calls can indicate the original outside line number of the group

and the incoming calls with the original called number can be terminated on the wireless terminals.This new protection scheme is worth a large-scale promotion for enterprise customer with private line of voice service

because of its good effect and less difficulties of implementation.