Voip Think- Voice over IP - Asterisk and SER - SIP IAX and H323

3CX VoIP Phone System, IP PBX for Windows
3CX PBX and Phone System for Windows
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  • VoIP Protocols

  • Telephones

  • QoS (Quality of Service)

  • Codecs

  • Asterisk

  • 3CX PBX

  • SER (Sip Express Router)

  • More information


      SIP Protocol  

        Architecture   Components   Messages   Error Messages   Headers   Addressing   SDP   Example  

    SIP Headers

    Headers are used to transport the information to the SIP entities. The main fields are:

    - Via: shows the transport protocol used and the request route, each proxy adds a line to this field
    - From: shows the address of the caller.
    - To: show the called user address of the request.
    - Call-Id: Unique identifier for each call and contains the host address. It must be the same for all the messages within a transaction.
    - Cseq: begins with a random number and it identifies in a sequential way each message.
    - Contact : shows one (or more) address than can be used to contact the user
    - User Agent: The client agent who deals the communication.

    Message Header
    Via: SIP/2.0/UDP;rport;branch=z9hG4bK646464100000007343c52679000020a600000e45
    Content-Length: 0
    Call-ID: 911D32E5-EEDF-4572-B0B2-61B294636E88@
    CSeq: 1 ACK
    From: "Prueba"<sip:20000@miasterisk.com>;tag=8922404614682
    Max-Forwards: 70
    Route: <sip:20001@>
    To: <sip:20001@miasterisk.com>;tag=as0a27b928
    User-Agent: SJphone/1.60.289a (SJ Labs)
    Contact: <sip:20100@>;expires=3600


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