Avaya Communication Manager Administrator's Manual page 1742

Feature Reference
Trunks and trunk groups
Analog tie trunks
The number of tie trunks in a connection and the technology of any multiplex systems used in the
facilities affect the maximum data transfer rate. Generally, for transfer rates up to 300 bps, a connection
can have 5 tie trunks 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 interface 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 media servers or 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.
Type of trunk
CO, FX, WATS
CPE
DID
DIOD
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Analog or
Direction Digital?
Incoming Either
Outgoing
Two-way
N.A. Either
Incoming Either
Incoming Either
Outgoing
Two-way
Administrator's Guide for Avaya Communication Manager
Transmits
Traffic supported digits?
Any kind of voice or No
data traffic.
Any kind of voice or No
data traffic.
Only voice and Yes
voice-grade data.
Any kind of voice or Only for
data traffic. incoming calls
November 2003