Gammu is an open-source SMS solution that is available on Linux and Windows platform. It is ideal for home or office use wherein one can setup a simple SMS-based system like a free SMS sender UI, or a complete dashboard with inbox, outbox, sent items, phonebook and call manager. One can also use it to pull content from a computer by the use of sms-based keyword commands.
The Gammu command line (and via a the Gammu PHP class) seems to accept and process command, such as –sendsms at a very slow rate. You can change how the program works by tinkering with the configuration file gammurc. In a test run, Huawei e153 modem took almost 10 seconds to finish sending a message. The connection type used was at19200, and later changed to at115200, giving a variable speed of 7 to 9 seconds a send. Interestingly, when used the at460800, it took more than 30 seconds to process an SMS message. Using a Bluetooth paired mobile phone is much faster than the GSM modem on the experiment. An at setting will let the Gammu software decide what is best for the device. For optimum use, benchmark the configuration one setting at a time.