John,
Usually we call port to T1/E1, for example 4-port E1 card, or 4-port T1 card.
Which means, the card support 4 T1/E1 lines, each of 1.56/2.1 Mbps lines, with-in each of switch there will be 24/32 channels…………
And each channel is a time-slot, which has a speed of 64kbps……
The ISUP CIC field refers to channel/time-slot…….
-Hoe this helps…….
Hari