Working with GSM modems
A GSM modem is a specialized type of modem which accepts a SIM
card, and operates over a subscription to a mobile operator, just
like a mobile phone. From the mobile operator perspective, a GSM
modem looks just like a mobile phone.
When a GSM modem is connected to a computer, this allows the
computer to use the GSM modem to communicate over the mobile
network. While these GSM modems are most frequently used to
provide mobile internet connectivity, many of them can also be used
for sending and receiving SMS and MMS messages.
GSM modem can be a dedicated modem device with a serial, USB or
Bluetooth connection, or it can be a mobile phone that provides GSM
For the purpose of this document, the term GSM modem is used as a
generic term to refer to any modem that supports one or more of the
protocols in the GSM evolutionary family, including the 2.5G
technologies GPRS and EDGE, as well as the 3G technologies WCDMA,
UMTS, HSDPA and HSUPA.
A GSM modem exposes an interface that allows systems such as
NetDecision to send and receive messages over the modem interface.
The mobile operator charges for this message sending and receiving
as if it was performed directly on a mobile phone. To perform these
tasks, a GSM modem must support an “extended AT command set” for
sending/receiving SMS messages, as defined in the ETSI GSM 07.05
and and 3GPP TS 27.005 specifications.
A GSM modem could also be a standard GSM mobile phone with the
appropriate cable and software driver to connect to a serial port
or USB port on your computer. Any phone that supports the “extended
AT command set” for sending/receiving SMS messages, as defined in
ETSI GSM 07.05 and/or 3GPP TS 27.005, can be supported by the
NetDecision. Note that not all mobile phones support this modem
interface. Due to some compatibility issues that can exist with
mobile phones, using a dedicated GSM modem is usually preferable to
a GSM mobile phone. This is more of an issue with MMS messaging,
where if you wish to be able to receive inbound MMS messages with
the gateway, the modem interface on most GSM phones will only allow
you to send MMS messages. This is because the mobile phone
automatically processes received MMS message notifications without
forwarding them via the modem interface. It should also be noted
that not all phones support the modem interface for sending and
receiving SMS messages. In particular, most smart phones, including
Blackberries, iPhone, and Windows Mobile devices, do not support
this GSM modem interface for sending and receiving SMS messages at
all. Additionally, Nokia phones that use the S60 (Series 60)
interface, which is Symbian based, only support sending SMS
messages via the modem interface, and do not support receiving SMS
via the modem interface.
The NetDecision Script Language implements the following GSM modem