Microsoft® Mobile Development Handbook

Making Voice and Data Calls

Data connections such as ActiveSync and WiFi are essentially always on as long as their hardware is activated. If you want to use a telephone network to send data using GPRS, CDMA, or Universal Mobile Telecommunications System (UMTS), you must programmatically establish a connection when required. If you use an HttpWebRequest or use Web Services code, the Microsoft .NET Framework runtime will attempt to establish an Internet connection for you automatically; when using lower-level networking technologies, you must create the connection yourself. Similarly, if as part of your application you want to initiate a voice call for the user, you must know the appropriate native APIs to call because the Microsoft .NET Compact ...