DEFINITY ECS Release 8.2
Administrator’s Guide
555-233-506 Issue 1
April 2000
Features and technical reference
1568Trunks and Trunk Groups
20
receive one of these start dial signals, it can be administ ered to sen d digit s aft er an
administered interval. (This time-out interval is th e amount of time that the
originating switch waits before sending digits.)
Analog tie trunks
The number of tie trunks in a connection and the technology of any multiplex
systems used in the facilities affect the ma ximum data transfer rate. Generally, for
transfer rates up to 300 bps, a connection can have 5 tie trunk s in tandem. For data
rates of 301–2,400 bps, a connection can have up to 3 tie trunks in tandem. For
data rates of 2,401–4,800 bps, a connection can have up to 2 tie trunks in tandem.
Analog tie trunks used in unswitched connections can support up to 9,600 bps.
Digital tie trunks
The digital tie trunk is a high-speed and high-volume trunk in te rfa ce to a T1 or E1
carrier. It uses a digital signal level 1 (DS1) protocol. By multiplexing 24 64-kbps
digital channels onto a single 1.544-Mbps T1 carrier, or 32 64-kbps digital
channels onto a single 2.048-Mbps E1 carrier, DS1 offers an economical
alternative to the analog tie trunk as well as a high-speed fully digital (without
modems) connection between the switches.
The maximum per-channel data rate for DS1 is 64 Kbps, and DS1 trunks can carry
voice, voiceband data, or high-speed data communications.
WATS — Wide Area Telecommunications
Service
Outgoing WATS service allows calls to certain areas (“WATS bands”) for a flat
monthly charge. Incoming WATS trunks allow you to offer toll-free calling to
customers and employees.
Applications for different trunk types
To help you select the right type of trunk for a specific application, the following
table gives you an overview of key characteristics of different trunk groups.
Remember that all analog trunks can carry only voice and voice-grade data.