AT&T MERLIN LEGEND Communications System PBX System Planning Manual page 39

Control Unit
Mode of Operation
See System Reference for more
information on modes.
See System Reference for information
on trunk types.
2-10 System Operating Conditions
Your system is registered with the FCC to operate as either a Private Branch
Exchange (PBX) or Hybrid system. However, you can program the system to
operate in any of three modes:
Hybrid/PBX
Key (the factory setting)
Behind Switch
The mode of operation determines
how outside trunks are provided to users
the types of operator consoles allowed
the features available and how they work
Note: This book applies only to systems in the Hybrid/PBX mode. To plan a
system in either the Key or Behind Switch mode, use Key System P/arming.
Hybrid/PBX Mode
The Hybrid/PBX mode handles large volumes of calls and telephone users, and
offers the most flexibility of the three modes. Outside lines, called trunks, can be
loop-start, ground-start, Direct Inward Dial (DID), DS1, or tie. The outside trunks
can be grouped in pools for shared use. In addition, outside trunks can also be
assigned to line buttons on multiline telephones for users who require a personal
line.
Users access inside lines and outside trunks via System Access buttons. To
make an outside call, the user enters a dial-out code, usually a 9, and the
system automatically selects an available trunk. The Automatic Route Selection
feature determines which trunk is used for each type of outgoing call.
Incoming calls can be handled by either a direct-line console (DLC) or a queued
call console (QCC), or a combination of both. Calls handled by QCCs are
directed to a QCC queue, where they are held until an operator is available.
Planning Form Instructions
Check "Hybrid/PBX" under the "Set System Mode" heading on Form 1.