Stands for "Rich Communication Services."
RCS is a communication technology for sending and receiving text messaging on smartphones. It is an extension of older SMS text messaging technology that increases message length and adds modern features, like delivery receipts and high-resolution media. Most mobile phone carriers and Android smartphones can use RCS messaging, but iPhones still lack support.
Unlike SMS and MMS messaging, which use the cellular voice network to deliver messages, RCS uses a mobile phone's LTE or 5G Internet connection to send text and multimedia messages. It addresses several shortcomings of SMS and MMS messaging and adds new features common in proprietary messaging apps. The primary improvements made by RCS include:
- No limit on the length of a text message, instead of the SMS limit of 160 characters.
- High-resolution media sharing for images, audio, and video, unlike the highly-compressed low-resolution media sent over MMS.
- Delivery and Read receipts that indicate whether a message has been successfully delivered and when it has been read by the recipient.
- Live typing indicators inform you when someone in a thread is composing a message.
- Location sharing allows you to share a location on a map to help meet up or give directions.
- File sharing allows you to share documents and files with other participants in a message thread.
Many of the features added by RCS are present in other mobile messaging apps like Apple's iMessage, WhatsApp, and Facebook Messenger. RCS is supported directly by the mobile carriers and uses your phone number for identification, so it does not require a separate account or app — if two people use an RCS-compatible messaging app to exchange text messages, they will automatically use RCS and can access its additional features; if only one participant supports RCS, the apps will fall back to SMS or MMS messages instead. Most mobile carriers and Android smartphones support RCS, but the lack of support on the iPhone creates a barrier to the universal adoption of RCS.