Note: The content of this SIG follows the convention described in OpenHarmony's PMC Management Charter [README](/zh/pmc.md).
## SIG group work objectives and scope
### work goals
- Provide basic communication capabilities of cellular mobile networks such as SIM card, network search, cellular data, cellular call and short MMS, manage multi-type call and data network connection, and provide convenient and consistent communication API for application developers.
### work scope
- Telephony core service: initializes the RIL Manager, SIM card module, and network search module.
- Call Manager module: manages three types of calls – circuit switched (CS), IP multimedia subsystem (IMS), and over the top (OTT) calls. It is responsible for applying for the audio and video resources required for a call and resolving conflicts in a multi-channel call.
- Cellular call module: implements basic calls over carrier networks.
- SMS & MMS module: provides the capabilities of sending and receiving short message service (SMS) messages and encoding and decoding multimedia messaging service (MMS) messages.
- State registry module: provides APIs to register and deregister an observer that listens for various callback events of the telephony subsystem.
- Meeting notification: [Subscribe to] (https://lists.openatom.io/postorius/lists/dev.openharmony.io) mailing list dev@openharmony.io for the meeting link
- Meeting-Minutes: [Archive link address](https://gitee.com/openharmony-sig/sig-content)