Tie group has nothing to do with it. You have to set up Routing with proper Destination to be able to dial through T1 on MICS. Better yet, if you have P2P T1 set up as PRI and with MCDN you have to use SL-1 type Networking. On BCM you create a special Rout (001) to use PRI-A Trunks with 9 as access code and no absorption. As soon as MICS receives 9 + 11 digits it will grab its own PRI and dials out your number. To set that up you have to be really familiar with Norstar and BCM Privet Network Programming otherwise I would suggest to call a knowledgeable tech.