AT&T MERLIN LEGEND Release 4.0 Feature Reference page 415

Feature Reference
system's toll restriction is guaranteed to be received by the far-end
switch.
A PRI line's far-end disconnect signal provides a reliable indication
when a call ends, and a new call cannot be initiated until the line has
been released from the prior call on both ends. This prevents a user
on a loop-start trunk, waiting off-hook for the restoration of dial tone
after a previous call, from placing a second call before toll restriction
is reapplied.
Reliable Indication of Far-End Disconnect. This prevents an incoming
call from being blocked because a trunk has not been released when a
call is ended.
Features offered by PRI are as follows:
Connectivity to 5ESS Generic 6 (Release 2.0 and later). The benefits of
5ESS connectivity include making local calls, operator access (local,
common carrier, and operator-assisted calls), common carrier selection,
and 5ESS PRI services.
Routing by Dial Plan (Release 2.0 and later). Routing by Dial Plan
supports call handling similar to Direct Inward Dialing (DID). It is
especially suitable to supporting the Dialed Number Identification Service
(DNIS), a service attribute of the Megacom 800 service that routes
incoming 800 or 900 calls according to customer selected parameters,
such as area code, state, or time of call. For example, a customer can
specify that calls received from a particular area code should be routed
to a specific individual or group responsible for accounts in the area.
Routing by Dial Plan performs digit analysis on incoming calls, matches
to Called Party Numbers (CdPNs), and delivers the calls to the
destination endpoints based on the respective Called Party Numbers. It
also allows multiple calls to the same directory number, that is, multiple
concurrent incoming calls with the same Called Party Number can be
delivered to an endpoint simultaneously.
Call-by-Call Service Selection (Release 2.0 and later). This feature
allows maximum utilization of communications lines, providing more
services with fewer lines. Call-by-Call Service Selection provides more
than one PRI service (such as Megacom WATS, ACCUNET Switched
Digital 56/64, SDN, OUT WATS, and Virtual Private Network Access) for
each B-channel. Based on the number dialed and the bearer capability
(voice, data, or both), the system chooses what service is used. If a caller
requests operator service, the system bypasses Call-by-Call Service
Selection.
Restriction Code Handling for FTS2000 Network (Release 2.0 and
later). FTS2000 network users can have restriction codes applied to their
extensions. A person who attempts to place a call that exceeds the set
restriction level must first enter an restriction code. If no code is entered,
Primary Rate Interface (PRI) and T1
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