Android phones seem to support 2 kinds of SMS: Text SMS and Data SMS. I think I know what a text SMS is, but what is a Data SMS and how / for what is it used (btw as far as I can tell Data SMS are not MMS)?
I recognize that this might not be Android specific, but I encountered the term first on my Android handset, so here I go. If this is more general and better moved to a different forum feel free to suggest so...
Data SMS messages are sent through the data network, over your 2G / 3G data connection, just like all other data such as internet traffic. Normally SMS messages have their own method of transport, the details of which you can check out on Wikipedia.
A perfect example for data SMS use is when your recipient must pay to receive your text message even though you may have unlimited texting. By using a data SMS service, all extra charges are avoided and the amount of data used by SMS messages is insignificant compared to even lite web page viewing.
I think Data SMS messages are sent not only through the data network (over your 2G / 3G data connection), but also through GSM as Text SMS. The PDU of a text message has a User Data Headers (UDH) that defines a specific port on a handset. Refer to this link: http://developers.esendex.com/Concepts-and-Patterns/Sending-SMS-to-a-Specific-Port
User named www.jensolsson.se is correct. OP is also correct it's not really a Android subject perse, it's more of a cellular technology subject. Since we are not sticking to Android is will share my experience with data sms in the Linux side of things. I use data sms for a custom IoT type of communication to do very low level control of the devices such as rebooting or restarting a misbehaving application. I use the mmcli tool to send and receive the data sms messages. The data value that I send is a bitmasked binary value (from memory a 64bit value) that represents the operational status of the device and its applications. A good place to start is looking at the mmcli man page. I learned of this capability while learning how to use mmcli to send and receive text messages using mmcli. My text messages were becoming giant JSON strings. Since I controlled both ends, I developed a custom protocol that only needs a single 64bit symbol with many values encoded in to it.
https://www.freedesktop.org/software/ModemManager/man/latest/mmcli.1.html
Data SMS is just like regular SMS. Contrary to what other answers to this question which implies the data smses dont use the 3g/4g data connection at all. You can actually disable both mobile data and wifi on your phone and you can still send and receive data sms.
Data SMS is a feature for app to app communication. Historically it was also used for example to change certain aspects of the phone. For example adding operator logo, ring tones etc.
