Message Type - Huawei U-SYS MRS6100 Technical Manual

Technical Manual
U-SYS MRS6100 Media Resource Server
RSVP (Resource ReServation Protocol) for reserving network resources
RTP (Real-Time Transmit Protocol) for transmitting real-time data and providing
QoS feedback
RTSP (Real-Time Stream Protocol) for controlling the transmission of media
streams in real time
SAP (Session Announcement Protocol) for advertising multimedia sessions
through multicast
SDP (Session Description Protocol) for describing multimedia sessions However,
the functionality and operation of SIP does not rely on any of these protocols
Transport-layer support: SIP is borne over the IP network. The network-layer
protocol is IP and the transport-layer protocol is UDP

5.3.4 Message Type

SIP messages are encoded in text form. There are two types of messages, request
messages and response messages.
I. Request messages
Request messages are SIP messages sent from a client to a server, for invoking
particular operations. Request messages include INVITE, ACK, OPTIONS, BYE,
CANCEL and REGISTER messages. Functions of these messages are listed in
Table 5-10.
Table 5-10 Request messages
Request
messages
INVITE
ACK
BYE
CANCEL
The INVITE message indicates that the user is being invited to
participate in a session. The message body contains a
description of the session to which the callee is being invited.
For two-party calls, the caller indicates the type of media it is
able to receive as well as their parameters. A success response
must indicate in its message body which media the callee
hopes to receive and may indicate the media the callee is going
to send.
The callee can acknowledge the participating of the caller and
send the 200 (OK) response, according to the Call-ID or the
identifier in the session description.
The ACK request confirms that the client has received a final
response to an INVITE request. ACK is used only with INVITE
messages.
UAC uses BYE to indicate to the server that it hopes to release
the call.
The CANCEL request cancels a pending request, but does not
affect a completed request. (A request is considered completed
if the server has returned a final status response.)
Huawei Technologies Proprietary
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Chapter 5 MGCP and SIP
Message meanings