Developing Modem Applications
80-99208-1 Rev. D 5-33
Note
You can also hang up an asynchronous data call by de-ass ert ing DTR.
However, if DTR is high on only one port and you then de-assert it, the
modem will begin its shutdown sequence.
Mobile-Terminated Asynchronous Data Calls
The GSP-1620 modem lets the app lication device (DTE)
connected to it receive an asynchronous data call. It is the
responsibility of the DTE application to keep the mode m
powered up if it is to receiv e incoming asynchronous data
calls.
Here is what happens during a mobile-terminated
asynchronous call:
• The host server dire cts a host modem to call the
GSP-1620 modem (DCE), using the Dial Numbe r (DN)
assigned to the GSP-1620 modem by the Service Provider.
• The incoming call toggles RI and displays RING to the
appropriate port.
•The
ATA command tells the GSP-1620 modem (DCE) to
answer an incoming call (for details, see An swer Incoming
Call (A) on page 6-18; also see Automatic Answer (S0) on
page 6-25).
• How the modem answers the call depends on how the
ports are configured. Port behavior for incoming
asynchronous calls is the same as for packet calls. For
details, see Answering Cal ls Using the Data Port On ly on
page 5-28 and Answering Calls Using the Data and
Control Ports on page 5-29.