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Operational Details
Transfer Codes
When the Polling Controller receives routing code, it translates it into a transfer
code and sends the transfer code to the SLSS. These codes determine the SLSS
port to which a call is routed.
The SLSS arrives from the factory with unpublished transfer codes which you
can change. (Please refer to Tables 2 and 3.) Each SLSS port must have a transfer
code of one to four digits in length.
If you are using the SLSS as a standalone unit, the transfer codes can be sent
without a Polling Controller from a DTMF telephone or modem. (Please see
Standalone SLSS Operation for more detail.)
Calling Party Supervision
The U.S. telephone network typically uses Calling Party Supervision. This means
that even though the called party hangs up, she/he may be reconnected to the
calling party when her/his phone is taken off-hook again. The calling party must
hang up in order for the called party to be fully disconnected to initiate a new
call. The telephone network will time out and automatically disconnect the call
within 5 - 20 seconds, depending on network design. This will allow the called
party to get dial tone when she/he goes off-hook again.
To circumvent this problem, when the SLSS senses a priority interrupt it
immediately signals the Polling Controller to disconnect the original polling call.
This ensures that the user initiating the priority will be able to complete the
priority call.
If for any reason the interrupted call cannot be terminated within 5 seconds, a
busy tone is returned to the priority caller. The caller should then hang up for a
few seconds before trying the call again.
Outgoing Calls from the SLSS
The SLSS allows DTMF and rotary dialing on outgoing calls.
Outgoing Telephone Calls—SLSS Idle
When the SLSS is idle and a phone goes off-hook, the port is switched to the
Central Office line and the caller hears dial tone. When the phone goes on-hook,
the SLSS is idle again. (When the SLSS is idle, the ports connect to a local battery
feed.)
Outgoing Telephone Calls—SLSS Active
In Total Priority Mode a higher-priority port is given access to the line whenever
it goes off-hook.
Reference Manual
Chapter 5: Polling Controller and SLSS Operation/Features
40-400-00031, Rev. A
Page 27