Avaya Communication Manager Administrator's Manual page 1740

Feature Reference
Trunks and trunk groups
DIOD — Direct Inward/Outward Dialing
DIOD trunks are two-way trunks that transmit dialed digits in both directions. Thus, use DIOD trunks
when you want a two-way trunk group with the convenience of direct inward dialing for incoming calls.
DIOD trunks are used mostly outside North America, and typically they connect the server running
Communication Manager to a local central office.
In North America, use tie trunks for applications that require two-way transmission of dialed digits. In the
U.S., trunks that transmit digits in both directions are sometimes called "smart trunks" and are
administered as T1 tie trunks.
FX — Foreign Exchange
An FX trunk is essentially a CO trunk that connects Communication Manager directly to a central office
outside your local exchange area. Use FX trunks to reduce long distance charges if your organization
averages a high volume of long-distance calls to a specific area code.
IP Trunks — Internet Protocol Trunks
IP trunks allow Avaya Communication Manager to route voice calls and faxes over a local- or wide-area
TCP/IP network. Use IP trunks to reduce long-distance charges by routing calls over the Internet or your
intranet.
NOTE:
The origin and destination media servers or switches must both have the special hardware
and software needed to route telephone calls over IP networks. See the Administration for
Network Connectivity for Avaya Communication Manager for more information.
ISDN — Integrated Services Digital Network
ISDN trunks are digital trunks that can integrate voice, data, and video signals and provide the bandwidth
needed for applications such as high-speed data transfer and video conferencing. ISDN provides
end-to-end digital connectivity and uses a high-speed interface that provides service-independent access
to switched services. Through internationally accepted standard interfaces, an ISDN provides circuit- or
packet-switched connectivity within a network and can link to other ISDN-supported interfaces to
provide national and international digital communications. ISDN trunks can also efficiently combine
multiple services on one trunk group.
PCOL — Personal Central Office Line
A personal central office line is one dedicated trunk that links a group of phones to the local central office
or to another media server or switch in a private network. A PCOL group can have 1–16 phones, and each
phone can have one or more appearances for the personal central office line. You may administer a PCOL
group as a CO, FX, or WATS trunk group. Use a PCOL line when one or more users need a direct,
dedicated connection to the public network or to another server or switch.
1740 Administrator's Guide for Avaya Communication Manager
November 2003