Call Flow - Huawei U-SYS MRS6100 Technical Manual

Technical Manual
U-SYS MRS6100 Media Resource Server
st
The 1 line: 200 indicates the successful receipt of the command. 693585490 is a
transaction identifier which is the same as the transaction identifier contained in the
CreateConnection command that triggers this response. CRCX OK is a
commentary.
nd
The 2 line: The connection identifier is 1607901.
rd
The 3 line: Null, indicating what is preceded is an SDP session description.
th
The 4 line: The SDP protocol version is 0. It is the local connection descriptor at this
time.
th
The 5 line: c in the response identifies the connection information. IN refers to
network type in the form of a text string. The currently defined IN is Internet. IP4
indicates the type of connection address is IP4. 182.20.50.101 represents the local
network address of MRS6100.
th
The 6 line: Media description. audio indicates that the type of media is audio. (audio
is used for audio connections, and nas used for data access.) 10000 is the number of
transport layer port to which media streams are transmitted. RTP/AVP is the transport
layer protocol. Its value is associated with the type of address in the c line. For IP4, a
great number of media service streams are transferred over RTP/UDP. There are two
classes of protocols defined: RTP/AVP, audio/video application document,
transported over UDP; Udp, the DUP protocol. For audio and video signals, 8 0
represents the type of media payload defined in the RTP audio/video application
document. It means that all the formats carried in the session might be used, but the
first one is the default format for the session. At this time, the mapping relation from
RTP payload type to encoding is that 34 corresponds to the media encoding format
H263 .8 corresponds to the media encoding format PCMA. 0 corresponds to the
media encoding format PCMU. 18 corresponds to the media encoding format G.729.
4 corresponds to the media encoding format G.723.
th
The 7 line: Attribute. Attribute is the basic method for SDP extension. It can be
defined as session-level attribute or media-level attribute. There are two forms of
attributes:
a=<flag>, as feature attribute. It is a binary attribute, indicating the session has this
nature. For example, a=recvonly indicates the feature is "receive only".
a=<attribute>:<value>, as numeric value attribute. For example, a=ptime:20 indicates
the domain name of the media attribute is ptime and the value of the media attribute is
20.

5.2.6 Call Flow

I. MRS6100 registration flow
If the control protocol is MGCP, MRS6100 must register to MGC before it can proceed
to subsequent procedures. The registration flow of MRS6100 is shown in Figure 5-7.
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Chapter 5 MGCP and SIP