Simultaneous Voice and Data Connections
4/8/2010
Connection Manager supports cellular networks that have simultaneous voice and data enabled. Support for simultaneous voice and data starts when Connection Manager receives from the Radio Interface Layer (RIL) a RIL_NOTIFY_SYSTEMCAPSCHANGED notification with the lpData parameter pointing to RIL_SYSTEMCAPS_VOICEDATA. Connection Manager stops supporting simultaneous voice and data if this RIL notification is not received.
A network has simultaneous voice and data when a data connection can transmit data while a voice call is in progress. This differs from suspend and resume functionality which suspends the data connection during a voice call and no data is transmitted.
If the network does not support simultaneous voice and data connections, Connection Manager disables the data connection when a voice call is active, or suspends the data connection if the connection is marked as suspend and resume capable in the registry. **
Simultaneous voice and data applies only to networks that have separate infrastructures for handling voice and data. Networks that do not differentiate between voice and data, for example Wi-Fi, do not have to support simultaneous voice and data. Newer cellular networks, for example 3G networks that support W-CDMA, are simultaneous voice and data enabled.