Call Flow - Huawei U-SYS MRS6100 Technical Manual

Technical Manual
U-SYS MRS6100 Media Resource Server
The 1st line: The SIP protocol. The protocol version is 2.0. The status code is 180.
Ringing is a descriptive phrase, referring to sending the ringing tone to the callee.
The 2nd line and 3rd line: Refer to "An example of request message".
The 4th line: This is a CSeq field, used to correlate the INVITE request with the
triggered responses and corresponding ACK and CANCLE requests. The CSeq field
in this response has the same meaning as that in the request described earlier. Both
are 1 INVITE, indicating the response is trigger by the previous request.
The 5th to 8th lines: Refer to "An example of request message".

5.3.6 Call Flow

I. Successful call flow
Generally, MRS6100 only acts as a UAS to receive call requests sent from an AS.
After a session is created, AS can modify session attributes with the reINVITE
command. AS can also record, play announcements, collect digits, and specify a
VXML script to perform a series of operations through the URL.AS can also execute
these operations with INFO messages, except for modifying session channel
attributes, as shown in Figure 5-14.
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Chapter 5 MGCP and SIP