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DEFINITY ECS Release 8.2
Administrator’s Guide
555-233-506
Issue 1
April 2000
Features and technical reference
1565Trunks and Trunk Groups
20
CAMA — Centralized Automatic Message
Accounting (E911)
CAMA trunks route emergency calls to the local community’s Enhanced 911
systems and provide Caller’s Emergency Service Identification (CESID)
information to the system. Public Service Answering Points (PSAP) use CAMA
trunks to determine the caller’s physical address.
NOTE:
Lucent does not recommend tandeming 911 calls.
When the CAMA feature is administered and a 911 call is placed from a
DEFINITY ECS station, DEFINITY software searches for the proper CAMA
Touch-Tone Receiver (TTR) resource in the port network (PN) where the CAMA
trunk group is located. If the proper CAMA TTR resource is not available in that
port network, the software checks any other available port networks for the
CAMA TTR. If none is found in the entire system, a busy tone is returned to the
calling party. However, if another trunk group is in the same routing pattern as the
CAMA trunk group, the call routes to the next available trunk group in the pattern.
For example, if a Central Office (CO) trunk group is used, then any available TTR
resource can be used and the call routes as a normal call over the CO trunk and the
public switched telephone network.
E911 systems use CESID information to identify the location of the calling phone.
The following features can cause incorrect CESID information to be sent with a
911 call.
Bridged stations
911 calls from a bridged extension will report the CESID of the principle station.
EAS agents
911 calls from an agent in an Expert Agent Selection (EAS) skill will report the
CESID of the physical station, not the logical agent.
Personal Station Access/Terminal Translation Initialization
When you use Personal Station Access (PSA) or Terminal Translation
Initialization (TTI) to associate a phone with another extension, the switch will
report the CESID of the extension — not the physical phone associated with it.
CO — Central Office
CO trunks transmit dialed digits for outgoing calls but not for incoming calls. Use
CO trunks when you want all incoming calls go to the same destination, such as
an attendant or a voice menu system. Individual users can place outgoing calls