MAYAH Communications

Technology Highlights

MAYAH CENTAURI II and MERK II go SIP

SIP: Session Initiation Protocol (RFC 3261)

This protocol is developed by the IETF (Internet Engineering Task Force) as an alternative to the H.323 Standard. Together with other protocols it allows to establish, control, terminate and modify point-to-point and multipoint connections.

As a client-server protocol, SIP is similar to HTTP. Its requests and responses are the text strings containing the information about conversation signalling.

SIP is responsible for the whole connection signalling, localisation of users and registration. Quality-of-Service, directory access, as well as description of the session and conferencing are not handled by SIP, rather by other protocols.
Modular structure of the SIP allows smooth co-operation with H.323. So the calling side can localize its partner and signalise, that a communication will be held over H.323 protocol.
Since SIP only provides the session framework (establishment, modification and termination of a connection) a number of protocols can be utilised to support and expand its functionality.

At present time some of the protocols integrated with SIP are:

-	RVSP (Resource Reservation Protocol) for reservation of network resources
-	TCP/UDP for transmission of SIP data
-	RTP for transmission of media data
-	RTSP as a support for session establishment
-	SAP for sessions with multiple participants
-	SDP to negotiate the transfer mode

>> see also previous issue of MAYAH Technology Highlights

An integration of telephone networks is provided by the ENUM protocol (Telephone Number Mapping), which enables a transparent connection establishment to and from IP based nets.

The complete separation of signalling and transport layer (i.e. of connection data and media data), as implemented in SIP allows for the user to establish a connection in a unified way without prior knowledge of the exact location of other participants and not depending on the nature of the transferred data.

The constantly growing acceptance of SIP - due to recent developments in fields like Internet telephony and UMTS - guarantees for a steady growth and expansion of infrastructure, which can then be used for other applications.