Messagefactory

MessageFactory serves as a personal messaging constructor. It's responsible for creating both the questions (requests) and the answers (responses) in the SIP conversation.

Creating a Request: When you want to initiate a call or simply say "hello" over SIP, you create a request. This process is similar to sending a letter – this request is your letter, complete with the address and the content.
// Create a basic SIP request to invite someone to a call
URI requestURI = addressFactory.createURI("sip:friend@example.com");
Request request = messageFactory.createRequest(
    requestURI,
    "INVITE", // The method
    callIdHeader, // Unique call identifier
    cSeqHeader, // Sequence number for ordering messages
    fromHeader, // Who the request is from
    toHeader, // Who the request is to
    viaHeaders, // "Via" headers specifying the transport route
    maxForwardsHeader // Limits the number of hops a request can make
);