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PN 2110036 Revision 1.0 05/11/99 1-1
1. Overview
1.1. CS-CDPD
The MP215 is a radio modem that supports CS-CDPD operation. CS-CDPD is a
specification for doing CDPD communications over a circuit-switched cellular
AMPS connection, and is described in detail in the CDPD Implementor Guideline
Part 1024 published by the CDPD Forum (now the Wireless Data Forum). Like
CDPD, CS-CDPD is a specialized service that must be available from a cellular
carrier in order for modem operation to be possible.
Basic CS-CDPD operation works as follows: the MP215 dials a pre-configured
1-800 number and establishes a circuit-switched cellular connection to a carrier’s
CS-CDPD modem bank. A connection is then established with the carrier’s
CS-CDPD router (a CMDIS), and the modem is registered on the CDPD network.
Regular IP-based data communication is now possible. Whether the modem is
connected via CDPD or CS-CDPD is transparent to the application at either end
of the communication link. After data transfer is complete, the cellular
connection is dropped, but the MP215 remains registered with the CDPD
network. In the event that data needs to be routed to or from the modem, either
the network or the MP215 initiates a cellular call and the data link is re-
established.
1.2. MP215 Operating Modes
The MP215 can be configured to operate as a CS-CDPD-only modem, a CDPD-
only modem, or an Autoswitching-modem that detects which service is available
and automatically switches from one service to the other, with preference for
CDPD. Autoswitching requires that various timers in the MP215 be configured
and reliable since operation of the modem is dependent on them. These timers are
pre-configured in the factory for optimum performance. Input from the cellular
carrier, system integrator, and Sierra Wireless is recommended if changes to these
timers are desired.