[USR-TC] RE: Busy signal!!!

Hello List: I finally got 3Com box (1-HiPer NMC, 2-Hiper ARC & 10-Hiper DSP) setup. Today, I connected a T1-PRI ISDN line to test. But as soon as I connect, the line gives busy signal. What setting causes this. /Please Help/. Thank you in advance. Kirti