Developing Modem Applications
80-99208-1 Rev. D 5-35
Roaming and Asynchronous Data Service
The GSP-1620 modem is capable of both “fixed” operation in
one location (for example, a building, tank, pipeline, or well)
or “mobile” operation for applications on trucks, rail cars ,
aircraft, or shipping containers.
For asynchronous or “dialed” data service, roaming operation
has the following characteristics:
• A host server can call the asynchronous Dial Number and
reach the modem, regardless o f which Gateway service
area it is currently located in (just as voice GSP-1600
Tri-Mode Phones can roam and be reached in any
Gateway service area).
• Roaming within a Gateway s ervice area is supported for
both mobile-originated and mobile-terminated
asynchronous data calls.
• Roaming between Gateway service areas is supported;
however, if the modem is in a call when it reaches the
edge of a service area, the call will be dropped and must
be re-established on the new Gate way.
• Once on a new Gateway, automatic re-registration will be
performed and a new data call can be established.
• Fixed (or dynamic) IP addresses are not required for
asynchronous data service as they are for packet data
service.
If service alerts are enabled, a service alert is sent out the
Data/Control port whenever the Service Provider or Gateway
changes. This includes the modem changing from roaming to
home service area and vice versa.