I have a customer that I installed an Avaya IP office for. They have 3 other sites that currently have BCM's (2 50's, 1 450). As of now, I have the sites talking to each other using the PRI. The issue is, is that when a call comes into the auto attendant of the 50 or 450 and the caller tries to dial an IPO extension, they get a message that says "you have entered an invalid extension". Any suggestions as to how I can get this to work?