Sip session initiation protocol

Location Service: A location service is used by a SIP redirect or proxy server to obtain information about a callee's possible location s.

Sip server

Section In this example, Bob decides to answer the call. In general, the end-to-end media packets take a different path from the SIP signaling messages. In SIP, as in HTTP, the user agent may identify itself using a message header field User-Agent , containing a text description of the software, hardware, or the product name. SIP can be used to establish two-party unicast or multiparty multicast sessions. For a UAC, these rules govern the construction of a request; for a UAS, they govern the processing of a request and generating a response. Section 13 discusses how sessions are initiated, resulting in one or more SIP dialogs.

SIP can be used to initiate a session that uses some other conference control protocol. A redirect server allows proxy servers to direct SIP session invitations to external domains.

Sip phone

Alice and Bob's media session has now begun, and they send media packets using the format to which they agreed in the exchange of SDP. After this information is exchanged and acknowledged, all participants are aware of the participants' IP addresses, available transmission capacity, and media type. A call stateful proxy is always transaction stateful, but the converse is not necessarily true. SIP messages are either requests or responses. SIP is the signaling protocol that enables one party to place a call to another party and to negotiate the parameters of a multimedia session. Display names are described in RFC [ 3 ]. SIP is used to invite one or more participants to a session, while the SDP-encoded body of the SIP message contains information about what media encodings for example, voice, video the parties can and will use. As defined, a callee can be invited several times, by different calls, to the same session. User capabilities: In this step, the media and media parameters to be used are determined. An example would be sips:bob biloxi. Header field rows consist of a header field name and zero or more header field values.

Sequential Search: In a sequential search, a proxy server attempts each contact address in sequence, proceeding to the next one only after the previous has generated a final response. SIP does not offer conference control services such as floor control or voting and does not prescribe how a conference is to be managed.

Discussion of transactions can be found in Section Further, as older Private Branch Exchanges PBXs and network switches are phased out, industry is moving toward a voice networking model that is SIP signaled, IP based, and packet switched, not only in the wide area but also on the customer premises [2, 3].

Sip session initiation protocol

For example, SIP can locate a user and deliver an opaque object to his current location. A transaction is a request sent by a client transaction using the transport layer to a server transaction, along with all responses to that request sent from the server transaction back to the client.

how sip protocol works

The reasons for this special handling for INVITE will be discussed later, but relate to the reliability mechanisms in SIP, the length of time it can take for a ringing phone to be answered, and forking.

Call Leg: Another name for a dialog [ 31 ]; no longer used in this specification.

Sip definition

If the same primitive is used to deliver a photo of the caller as well as the session description, a "caller ID" service can be easily implemented. Here are some simple requests the protocol can make: Invite- Which starts a dialogue that will initiate a call. A TU that creates a client transaction can also cancel it. Server: A server is a network element that receives requests in order to service them and sends back responses to those requests. As a result, although DNS and location service lookups were required to route the initial INVITE, the Ringing response can be returned to the caller without lookups or without state being Rosenberg, et. This request is proxied back to the example. For example, if the biloxi. The complete set of SIP message details for this registration example is in Section They may be implemented as separate servers configured on the Internet or they may be combined into a single application that resides in a physical server. SIP is an agile, general-purpose tool for creating, modifying, and terminating sessions that works independently of underlying transport protocols and without dependency on the type of session that is being established. SIP can support any type of single-media or multi-media session, including teleconferencing. Cores, except for the stateless proxy, are transaction users. A proxy server needs to consult a DNS server to find a proxy server for the target domain.
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Session Initiation Protocol (SIP)