AT&T MERLIN LEGEND Release 4.0 Feature Reference page 440

Feature Reference
Call Waiting
Callback
Camp-On
Conference
Coverage
Calling Restrictions
Group Calling
HFAI
Hold
Music On Hold
Paging
440
Primary Rate Interface (PRI) and T1
Call Waiting is provided on PRI lines at extensions so programmed. The
call-waiting tone is not blocked from PRI at an extension if turned on.
Until the call is answered, answer supervision is not returned to the
network, and the caller hears regular ringback as opposed to
call-waiting ringback.
Call Waiting does not work with data calls.
Callback cannot be used to request a busy PRI line assigned as a
personal line. A pool with PRI lines as members may be queued for. An
idle PRI line is not considered an available pool member unless a check
determines that it is associated with an available B-channel. Even if a
B-channel is available when the pool selects a line for a queued call,
there may be none available when it is time to send a setup message to
the network. Or, after the setup message is sent, the network may
determine that the B-channel proposed by the system is not available.
In either case, the call fails and a fast busy tone is applied.
Some applications (such as desktop video system) that use data lines
may work improperly when de-queuing data facilities requested by
Callback.
The MERLIN LEGEND Communications System does not support
Camp-On onto data calls.
The MERLIN LEGEND Communications System does not support
Conferencing onto data calls.
Data calls do not follow Coverage Delay intervals. All data calls are
answered with Immediate Ring.
Outward and toll restrictions do not work with T1 lines emulating tie
trunks when the lines are set to Tie-PBX or Tie Switched 56 Data. Use
Automatic Route Selection or pool dial-out codes instead.
A PRI line that is a member of a B-channel group programmed for
Routing by Dial Plan should not belong to a calling group. A line that is
part of a B-channel group included in a calling group should not be
programmed for Routing by Dial Plan.
Incoming calls on a line that is a member of a B-channel group
programmed for Routing by Dial Plan are not eligible for answer by
Hands-Free Answer on Intercom (HFAI).
Data calls can not be placed on hold.
Music on Hold cannot be used with data calls.
If the extension for an incoming call matches a group paging extension,
the call is treated as an unassigned Direct Inward Dial (DID) call.
Data lines cannot be used for paging.