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MERLIN LEGENDCommunications System Release 6.1
System Planning
555-661-112
Issue 1
August 1998
Data Communications
Page 5-28Assigning Lines/Trunks to Data and Video Stations
5
■ Analog/Digital Tie. This trunk type “ties” two telephone switching systems
together, providing access to all telephones or data equipment on each
system. Analog Tie trunks are used for data communication with modem
data stations connected to a system at a different location, such as a
different floor of a building, a different building, or a different city or state.
Analog Tie trunks connect to a jack on a 400EM module in the control unit.
Video calls are not made over analog Tie lines/trunks.
Digital Tie trunks are used for digital data communications, such as G4 fax
and videoconferencing, with digital data/video stations connected to a
system at a different location, such as a different floor of a building, a
different building, or a different city or state. Digital Tie trunks are emulated
by T1 facilities connected to a 100D module in the control unit. Video and
digital data calls may be made over digital Tie lines/trunks.
■ Direct Inward Dial (DID). Incoming calls reach specific individuals or
facilities in the system without the help of a system operator. DID trunks are
available only in Hybrid/PBX mode. A DID trunk is used to receive
incoming calls from outside modem data stations. It is not used for
outgoing calls. A DID trunk connects to a jack on an 800 DID module in the
control unit. Video calls are not made over DID lines/trunks.
■ Digital Signal 1 (DS1). This facility carries digital signals in the DS1
format. A DS1 facility can be used for communication with outside digital or
modem data stations, including video systems. A DS1 facility connects to
the jack on a 100D module in the control unit. Even though there is only
one physical jack, the 100D module supports up to 24 logical endpoints for
voice and data calls; each DS0 channel in the DS1 signal corresponds to a
trunk or logical ID.
A DS1 facility provides either T1 (including T1 Switched 56 for digital
data/video calls) or PRI access:
— T1 (factory setting). The 24 channels on a T1 facility can be
programmed individually in any combination to emulate a loop-start,
ground-start, E&M tie, DID, or Switched 56 digital data trunk, so a
single 100D module can replace 24 outside lines/trunks. When T1
Switched 56 service is used, high-speed video connections at data
rates of 56-kbps per channel (112-kbps for 2B Data) are possible.
— PRI. The standard format for ISDN services provided by connection
to a 5ESS central office (CO) switch or a 4ESS or DEFINITY toll
switch. PRI facilities provide several benefits, including increased
speed of data calls to an outside destination, INFO-2 automatic call
identification (ANI) service, dynamic B-channel assignment,
improved toll restriction, reliable indication of far-end disconnect,
and improved SMDR. Twenty-three channels can be programmed
for individual services (Channel 24 is reserved for signaling
purposes). PRI facilities may also be used for high-speed video calls
at data rates of up to 64-kbps per B-channel (128-kbps total for 2B
Data).