7.5. Working with messaging: SMS

Mobile devices use the Short Message Service (SMS), a hugely popular and important means of communication, to send simple text messages with small amounts of data. Android includes a built-in SMS application that allows users to send, view, and reply to SMS messages. Along with the built-in user-facing apps and the related ContentProvider for interacting with the default text-messaging app, the SDK provides APIs for developers to send and receive messages programmatically.

Because Android now supplies an excellent built-in SMS message application, you might wonder why anyone would bother building another one. The Android market sells several superior third-party SMS messaging applications, but SMS can do a lot more than text your contacts. For example, you could build an application that, upon receiving a special SMS, sends back another SMS containing its location information. Due to the nature of SMS, this strategy might succeed, while another approach like trying to get the phone to transmit its location in real time would fail. Alternately, adding SMS as another communications channel can enhance other applications. Best of all, Android makes working with SMS relatively simple and straightforward.