Huawei U-SYS MRS6100 Technical Manual page 75

Technical Manual
U-SYS MRS6100 Media Resource Server
a: rtpmap:8 PCMA/8000
a: rtpmap 0 PCMU/8000
a: rtpmap 4 G723/8000
a: rtpmap 18 G729/8000
The 1st line: The start line of the request is the INVITE request message. The request
URI,
sip:dialog.vxml.digits.vxml@182.20.50.1. The dialog.vxml. digits.vxml indicates the
AS requests MRS to parse the local script file digits.vxml. The IP address of MRS is
182.20.50.1. The SIP protocol version is 2.0.
The 2nd line: This is a From field. It indicates that the address of the request initiator
AS is <sip:4444@182.20. 20.105>. The tag is 1c25759. For all requests sent by one
AS to MRS, their From fields can be the same.
The 3rd line: This is a To field. It indicates that the IP address of MRS is
sip:dialog.vxml.digits.vxml @182.20.50.1. Its partial information is the same as the
request URI in the start line of the request.
The 4th line: This is a CSeq field. It is used to correlate the INVITE request with the
triggered responses and corresponding ACK and CANCLE requests.
The 5th line: This is a Call-ID field. It identifies an INVITE that is globally unique. The
Call-ID is call-973668242-23@182.20.20.105, in which 182.20.20.105 is the IP
address of the caller AS and call-973668242-23 is the local ID.
The 6th line: This is a Via field. It indicates the path taken by the request.SIP/2.0/UDP
represents the protocol used for the transmission, in which SIP is the protocol name,
2.0 is the protocol version number, and UDP is the transport layer.
182.20.20.105:5060 represents the request sender AS, in which 182.20.20.105 is the
IP address and 5061 is the port number.
The 7th line: This is a Contact field. It indicates that subsequent requests (BYE for
example) can be directly sent to <sip:4444@182.20.20.105>, without using the Via
field.
The 8th line: This is a 100rel extension. It provides an appropriate mechanism for the
reliable transportation of 100 response messages.
The 9th line: This is a Max-Forwards field. It indicates the maximum number of hops a
request can transit on the way to its destination is 70.
The 10th line: This is a Allow field. It gives a list of request types that can be supported
by the AS whose IP address is 182.20.20.105.
The 11th line: This is a Content-Length field. It indicates the length of the message
body.
The 12th line: This is a Content-Type field. It indicates that the message body is a
single one and is an SDP.
the current address
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Chapter 5 MGCP and SIP
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