22 Voice API Programming Guide — June 2005
Product Description
1.10 TDM Bus Routing
A time division multiplexing (TDM) bus is a technique for transmitting a number of separate
digitized signals simultaneously over a communication medium. TDM bus includes the CT Bus
and SCbus.
The CT Bus is an implementation of the computer telephony bus standard developed by the
Enterprise Computer Telephony Forum (ECTF) and accepted industry-wide. The H.100 hardware
specification covers CT Bus implementation using the PCI form factor. The H.110 hardware
specification covers CT Bus implementation using the CompactPCI (cPCI) form factor. The CT
Bus has 4096 bi-directional time slots.
The SCbus or signal computing bus connects Signal Computing System Architecture (SCSA)
resources. The SCbus has 1024 bi-directional time slots.
A TDM bus connects voice, telephone network interface, fax, and other technology resource
boards together. TDM bus boards are treated as board devices with on-board voice and/or
telephone network interface devices that are identified by a board and channel (time slot for digital
network channels) designation, such as a voice channel, analog channel, or digital channel.
For information on TDM bus routing functions, see the Voice API Library Reference.
Note: When you see a reference to the SCbus or SCbus routing, the information also applies to the CT
Bus on DM3 products. That is, the physical interboard connection can be either SCbus or CT Bus.
The SCbus protocol is used and the TDM routing API (previously called the SCbus routing API)
applies to all the boards regardless of whether they use an SCbus or CT Bus physical interboard
connection.