Chapter 5: Polling Controller Operation
Typical Call Sequence
When the Polling Controller and LSS are working together as a system, a
typical polling call from a host computer would progress as described below:
1. The host modem dials the polling call to access a modem on Port 3 of the
remote LSS, by dialing: 1-206-555-1212
∗
03
2. The PSTN processes the call and rings the remote LSS.
3. As soon as the Polling Controller recognizes the
∗
03
as a valid routing code,
it puts the calling modem on hold. Then it starts sending a translation of
the routing code (one to four unpublished DTMF digits). This translation
or transfer code, is sent at regular intervals through the network to the LSS.
The transfer code is sent repeatedly until the LSS acknowledges receipt or
until the calling modem times out and terminates the call.
4. The LSS answers the call at the end of the first ring and waits for a transfer
code (you can program the length of time that the LSS waits for the code,
the default is four seconds). If the LSS does not get a transfer code during
the wait period, it rings the default port, usually Port 1.
5. When the LSS recognizes the valid transfer code for Port 3, it rings Port 3
and sends an acknowledge tone, a typical modem answer tone, to the
Polling Controller.
Note:
The modem answer tone is used so that a Polling Controller can be
used to dial remote modems even when no LSS is installed.
6. When the Polling Controller recognizes the acknowledgment tone, it
removes the hold so that the calling modem will be listening when the
receiving modem on Port 3 answers the data call.
At this point, the Polling Controller and LSS have established a path for the data call,
enabling the calling and answering modems to communicate.
Polling Controller Reference Manual
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