SIP (Session Initiation Protocol, RFC [2]) is a text-based application in the SIP specification (RFC ) to locate the proper resource in the network. RFC Client-Initiated Connections in SIP October the Trust Legal .. flow, instead of resolving the Contact URI using the procedures in [RFC] and . Canonical URL: ; File formats: Plain Text PDF Discuss this RFC: Send questions or comments to [email protected]

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There is also an allow-events header to indicate event notification capabilities, and the accepted and bad event response codes to indicate if a subscription request has been preliminary accepted or has been turned down rf the notifier does not understand the kind of event requested.

There is a mechanism [36] to indicate that a SIP message is desired to be compressed. Several SIP extensions have been added to the basic protocol specification in order to extend its functionality.

Therefore, NAT traversal mechanisms are needed for both the signaling plane and the media plane. Retrieved December 5, In the IMS context, there are certain network entities i.

In the IMS every user agent is served by its P-CSCF, which is discovered by using the Dynamic Host Configuration Protocol or an equivalent mechanism when the user enters the IMS network, and all requests and responses from iettf to the user agent must traverse this proxy. However, as many words are repeated in different messages, the extended operations for SigComp [34] define a way to use a shared dictionary among subsequent messages.

The extension for service route discovery during registration [31] consists of a Service-Route header field that is used by the registrar in a 2XX response to a REGISTER request to inform the registering user of the entity that must forward every request originated by him or her.

PRACK, which is the iegf message used to tell the sender of a provisional response that his or her message has been received.

ITU-T A.5 reference justification

Moreover, there is also a mechanism for conditional event notification that allows the notifier to decide whether or not to send the complete Ffc message depending on if there is something new to notify since last subscription or there is not. This way the recipient of the message can decide whether or not to follow the reference to fetch the resource, depending on the bandwidth available.


Stream Control Transmission Protocol. In SIP, the route header field, filled by the sender, supports this functionality by listing a set of proxies the message will visit.

This request will be answered by the provisional reliable response code Session Progressthat will carry the SDP list of supported codecs by both the caller and the callee. Diversion Indication in SIP. IP multimedia concepts and services 2 ed.

When a proxy server receives a request from an untrusted entity and authenticates the user i. Accept-Contact to rfcc the desired destination user agents, Reject-Contact to state the user agents to avoid, and Request-Disposition to specify how the request should be handled by servers in the network i.

RFCs,,,,Errata Exist 7. The reliability of provisional responses extension [16] provides a mechanism to confirm that provisional responses such as the Ringing response codethat lets the caller know that the callee is being alerted, are successfully received. Merging the Internet and the Cellular Worlds 3 ed. It is then, when all the resources for the call are in place, when the caller is alerted.

Compression algorithms perform this operation by substituting repeated words in the message by its position in a dictionary where all these words only appear once. In this concept the caller states a set of constraints about the session i. This ffc, the registrar is able to discover and record the sequence of proxies that must be transited to get back rfcc the user agent. By using the user agent capabilities extension, [9] user agents terminals can describe themselves when they register so that others can search for them according to their caller preferences extension headers.

In the IMS it is possible for a user to have multiple terminals e. Other useful information describing rrc “Quality” of the document: Communicating Presentation Information in Internet Messages: Oracle Communications Converged Application Server does enforce uniqueness.

There are several standards that address this requirements, such as uetf following two for services interworking between the Ietr and the Internet i.

The REFER message also implies an event subscription to the result of the operation, so that the efc will know whether or not the recipient could contact the third person. In that case, user agents or servers use the Allow header to state which methods they support. This page was last edited on 10 Septemberat This RFC has been in existence since June All RFCs always remain ieyf on-line.


Numerous extensions exist and many more are proposed. When used in request-URIs, it indicates that the request is to be compressed, while in Via header fields it signals that the subsequent response is to be compressed.

Retrieved December 4, All this functionality is supported by new special header fields. An important source of failure is the inability to reserve network resources to support the session, so these resources should be allocated before the phone rings. Event notification is necessary in the IMS framework to inform about the presence of a user i.

The main functionality is supported by the P-Asserted-Identity extension header. Basic and Digest Access Authentication. Source routing is the mechanism that allows the sender of a message to specify partially or completely the route the message traverses. The necessity in the IMS of reserving resources to provide quality of service QoS leads to another security issue: The aim of event notification is to obtain the status of a given resource e.

Yes —Indicates that Oracle Communications Converged Application Server container directly supports the feature or specification. Feature development is prioritized according to general market trends, both observed and predicted. The event notification framework defines how a user agent can subscribe to events about the state of a resource, but it does not specify how that state can be published.

Current information, if any, about IPR issues: The efficient use of network resources, which may include a radio interface or other low-bandwidth access, is essential in the IMS in order to provide the user with an acceptable experience in terms of latency.

ITU-T work programme

Moreover, the SIP INFO method extension is designed to carry user information between terminals without affecting the signaling dialog and can be used to transport the dual-tone multi-frequency signaling to provide telephone keypad function for users. They are commonly obtained during the registration process: Likewise, if the server does not support any of the client’s required extensions, it will send an error response with a list of its unsupported extensions. They were designed specifically to meet the 3GPP requirements because a more general solution was not available.