Rich Communication Suite:

The RCS service is built around the idea of having a real time updated address book where both the presence and the capabilities of the contacts are displayed. The availability of the capability information of the contacts is the key part, which differentiates RCS from other services.

The address book is enhanced with the capability information (indicating the available communication services that can be triggered) and the presence attributes of the contacts (including availability, free text, geo-location, portrait icon). The capability information is the entry point to initiate rich communication services.

Building on IMS as the framework for service delivery, RCS utilizes the standardized IP Multimedia Subsystem (IMS) Core infrastructure to transmit the signaling and media traffic thus making use of the IMS registration and authentication procedures, interconnectivity between different operators, and fixed mobile convergence between Circuit Switched and Packet switched voice.

The RCS program focuses on a core feature set with the intention of realizing practical interoperability between different devices and network infrastructures.

RCS offers a number of benefits over today's communication applications including:

• A unified application being the entry point for all user services versus the number of different chat applications, voice applications, sharing applications.
• A single identity and a single number to identify the contacts and access all the services across any network and for any service.
• Presence and capability indication providing a better user experience.
• A standardized solution that is interoperable across any operator network.

RCS Versions:
The development in RCS has been incremental with the release of five versions so far.

RCS v1

In Release 1 of RCS, the service suite is defined for mobile users only. This means that the users have a mobile device with an embedded or installed client for RCS. The users have a direct relationship with a mobile operator.

The different features with RCS Release 1 can be grouped as follows:

• Enhanced Address Book - Capability and Presence capabilities.
• Enriched Call - Multimedia content sharing during call.
• Enhanced Messaging - Conversational view and chat capabilities.

RCS v2

The RCS Release 2 service is built around the capability enhanced address book as defined in RCS Release 1, but the same service is now made possible from a client using broadband access (BA).

Introducing a broadband access also results in the possibility of a user having multiple clients. Broadband access RCS clients are always deployed in conjunction with a mobile device that provides the user identity via its MSISDN (Mobile Station International ISDN Number).
The different features with RCS Release 2 can be grouped as follows:

• Broadband access to RCS services - Provides better experience for some RCS use cases (bigger screen for multimedia, easier handling via a keyboard for chat).
• Multi-device environment - Ability to receive different communication services over different devices simultaneously.
• Network Address Book - Introduced to allow synchronization of contacts between multiple terminals of the same user.

RCS v3

The RCS Release 3 service is built around the capability enhanced address book as defined in RCS Release 1 and Release 2, but the service is enhanced in different areas. The social presence is extended with new valuable information like geo-location, content sharing is now possible outside voice calls and new user experience is introduced via network based services. RCS Release 3 also enables a client using broadband access can be used as single client without the need for a mobile device.
The different features with RCS Release 3 can be grouped as follows:

• Social presence information enhancements - Introducing geo-location as part of the presence information.
• Enhanced messaging - Group chat with the list of participants shared between all parties.
• Network value added services (NVAS) - Network architecture defined to support invoking network services during chat and image share.
• Content sharing enhancement - Ability to share media inside and outside a voice call.
• Broadband access enhancement - Ability to access all RCS service through a broadband access device without the need for a mobile device.

RCS v4

RCS Release 4 builds further on the basis provided by the capability enhanced address book and the communication services that were defined in the previous Releases. Improvements are done in several areas though. A first set of enhancements is introduced to improve the RCS user experience when LTE (Long Term Evolution) or fixed access is being used. Enhancements in the messaging services, content sharing and network address book have also been part of RCS Release 4.

The different features within RCS Release 4 can be grouped as follows:

• Improved behavior when used over LTE access - Endorsement of VoLTE profile and ability to use the higher bandwidth provided by LTE to offer high quality video
• Messaging Evolution - Richer content by providing support for more media types and larger messages and support for multi-party text messages enabling “reply-all” functionality.
• Improvements for fixed access - Interworking between fixed RCS deployments (a number of typical home devices like TVs, set top boxes, tablets) and its mobile counterparts becomes possible.
• Contents enhancements - Interactivity with streamed video and shared images
• Improvements to network address synchronization.

RCS-e

RCS-e is the latest version of Rich Communication Suite (RCS) which will enable mobile phone end users to use instant messaging (IM), live video sharing and file transfer across any device on any network operator. RCS-e is built solely using the Session Initiation Protocol (SIP) OPTIONS request.

The key benefits of RCS-e for the end user are:

• Immediate information is displayed to the end user which service features are available for use.
• RCS-e is interoperable between mobile operators, which enable the end user to communicate and be connected with anyone.
• RCS-e service features are automatically available on the mobile device without the need to download and install software or create an account.