Developing Modem Applications
80-99208-1 Rev. D 5-17
• Reverse Link (Modem Transmit): 1610.73 to 1625.49
MHz
Short Messaging Service (SMS)The GSP-1620 modem supports IS-637 Mobile Terminated
Short Messaging Service (SMS). This is a separate featu re
from data (packet and/or asynchronous), and may be bille d
differently by the Service Provider.
Mobile-terminated SMS allows the host ap plication to “send”
numeric, alphanumeric, or binary messag es to the GSP-1620
modem. These messages are passed transparently out the
Data or Control RS-232 ports to the DTE (SCADA
application). The modem makes no attemp t to construct
ASCII character data. If “control” data is sent to the modem
via the SMS option, it will be passed along transparently to
the DTE application.
The SMS feature is fully functional even if the GSP-1620
modem is active on a data call, because SMS can be acce ssed
on the Control port. Therefore, the host application can send
command and control information to the modem either while
it is in a data session, or idle (not in a call).
Note
Check with your Globalstar service provider to see whether the SMS
feature is available.
SMS Alerts
SMS “alerts” are asynchronous message s sent out of the Data
or Control port to the DTE application upon receipt of the
SMS message (see Using Data and Control Ports on page 5-7
for a more detailed explanation).
Port configuration determines ho w SMS alerts are received:
• If the application is using the Control port, SMS alerts
are received on the Control port, even if a call is active.
• If the application is using the Data port only, the SMS
alert will be queued until th e data session is terminated.