The current production NexPath Telephony Server is available in a mini-tower version that has a maximum capacity of 48 ports (total of inside + outside lines). The NTS/ mini-tower systems will support up to 18 CO lines and 30 extensions, or six CBTI cards. Each system is composed of one or more of these circuit cards that provide the full functionality for the combined features of auto-attendant, voice-mail, conferencing, and call switching functions. This revolutionary, low-cost technology is made possible by special custom integrated circuits on each NexPath CBTI card to implement the telephone system features.

The difference between the NTS/ mini-tower systems and NTS/R or NTS/RX (rack-mount) systems is the maximum number of line cards that each will accept. The NTS/ systems use conventional motherboards, for lower cost, but will accept a maximum of six CBTI cards. The NTS/R and NTS/RX systems use passive backplane / single board CPU technology, which are industrial components and much less competitive in price. But the NTS/RX systems will accept up to seventeen CBTI cards in an industrial rack mount enclosure. The mid-size NTS/R will accept up to nine CBTI cards in a smaller enclosure..