Here are some links to companies that manufacture multi-COM port cards that can be used with CT. Cards which share a single IRQ line usually require a driver TSR, and this driver may or may not be supported by CT. CT does support some of the DigiBoard cards, however.

Byte Runner Technologies
Comtrol Corp.
Cyclades
Decision Computer Products
DigiBoard, Intl.
Globetek, Inc.
Lava Computer Mfg. Inc.
Quickpath Systems
SeaLevel Systems