This location service is then typically consulted by a proxy server that is responsible for routing requests for that domain. A dialog can also be in the « early » state, which occurs when it is created with a provisional response, and then transition to the « confirmed » state when a 2xx final response arrives. It enumerates all the extensions understood by the UAC. If the proxy is not responsible for that URI, it will not recurse on 3xx or responses as described below. Before sending a final response, the UAS can also send provisional responses 1xx to advise the UAC of progress in contacting the called user. A common ordering mechanism is to use the qvalue parameter of targets obtained from Contact header fields see Section When it arrives the second time, its Request-URI is identical to the first time, and other header fields that affect proxy operation are unchanged, so that the proxy would make the same processing decision on the request it made the first time.
|Système d’exploitation:||Windows, Mac, Android, iOS|
|Licence:||Usage Personnel Seulement|
If this parameter is not provided, the value of the Expires header field determines how long the URI is valid. Unless there is local policy specifying otherwise, the destination MUST be determined by applying the DNS procedures described in  as follows. No linear whitespace LWS is allowed in any of the elements. When a pre-existing route set is present, the procedures for populating the Request-URI and Route header field detailed in Section The CSeq number is incremented for each new request within a dialog and is a traditional sequence number. The procedures of Sections 8, 10, 11, 12, 13, 14, cohtactsay 15 coontactsay entirely with the UA core Section 9 describes cancellation, which applies to both UA core and proxy core.
This request may be forwarded by proxies, eventually arriving at one or more UAS that can potentially accept the invitation.
An intermediary entity contactsau acts as both a server and a client for the purpose of making requests on behalf of other clients. This proxy, in general, has no way of knowing the capabilities of that element, so it must restrict itself to the mandatory elements of a SIP implementation: Also note that UAs may send requests through a proxy server in order to reach a registrar if the two are separate elements.
Server Error — the server failed to fulfill an apparently valid request; 6xx: Similarly, the same software can act as a proxy server for one request and as a redirect server for the next request. Targets with equal qvalues may be processed in parallel.
If the request has a tag in the To header field but the dialog identifier does not match any of the existing dialogs, the UAS may have crashed and restarted, or may have received a request for a different possibly failed UAS. The last two digits do not have any categorization role. For example, SIP can locate a user and deliver an opaque object to his current location. Page 45 sur This means that a UAS based on this specification alone can never generate subsequent offers until completion of the initial transaction.
The complete list of SIP response codes is in Section Session Contactsah Protocol June With other 4xx responses, including those yet to be defined, a retry may or may not be possible depending on the method and the use case.
Such parameters may be useful for keeping state in the message rather than the proxy.
This section describes how to modify the actual session. The relative order of header fields with different field names is not significant.
Discussions Powa! – Page 45
Discussions dans le forum. Note that these may be different roles than the UAs held during the transaction that established the dialog. This is accomplished with a BYE, as described in Section This is independent of whatever transport protocols are used to send the response.
As potential targets are located through these services, their URIs are added to the target set. This response indicates that the proper response cannot be generated without support of a specific extension.
Ranger les posts par: Core designates the functions specific to a particular type of SIP entity, i. If this request contatcsay already part of a dialog, the proxy SHOULD insert a Record-Route header field value if it wishes to remain on the path of future requests in the dialog.
A route set can be learned, through headers like Record-Route, or it can be configured.
Topic Comment se servir du script …
The lines that follow are a list of header fields. A common way to create this value is to compute a sript hash of the To tag, From tag, Call-ID header field, the Request-URI of the request received before translationthe topmost Via header, and the sequence number from the CSeq header field, in addition to any Proxy-Require and Proxy-Authorization header fields scripr may be present. A client can also remove previous bindings or query to determine which bindings are currently in place for an address-of- record.
Content-Type contains a description of the message body not shown.
Blog de astuces-win – Page 7 – _THE blOg d’Δs†uc3s™ –
Rather, SIP provides primitives that can be used to implement different services. As a result, there is a two-phase exchange of SDP messages: While the Via header field tells other elements where to send the response, the Contact header field tells other elements where to send future requests.
SIP can also invite participants to already existing sessions, such contactsat multicast conferences. The transaction layer handles application-layer retransmissions, matching of responses to requests, and application-layer timeouts. In addition to DNS and location service lookups shown in this example, proxy servers can make flexible « routing decisions » to decide where to send a request.