6275
All method names, header field names, status codes, and option tags used in SIP applications are registered
6276
with IANA through instructions in an IANA Considerations section in an RFC.
6277
The specification instructs the IANA to create four new sub- registries under
http://www.iana.org/assignments/sip-6278
parameters: Option Tags, Warning Codes (warn-codes), Methods and Response Codes, added to the
sub-6279
registry of Header Fields that is already present there.
6280
27.1 Option Tags
6281
This specification establishes the Option Tags sub-registry under http://www.iana.org/assignments/sip-parameters.
6282
6283
Option tags are used in header fields such asRequire,Supported,Proxy-Require, andUnsupported
6284
in support of SIP compatibility mechanisms for extensions (Section 19.2). The option tag itself is a string
6285
that is associated with a particular SIP option (that is, an extension). It identifies the option to SIP endpoints.
6286
Option tags are registered by the IANA when they are published in standards track RFCs. The IANA
6287
Considerations section of the RFC must include the following information, which appears in the IANA
6288
registry along with the RFC number of the publication.
6289
• Name of the option tag. The name MAY be of any length, but SHOULD be no more than twenty
6290
characters long. The nameMUSTconsist ofalphanum(Section 25) characters only.
6291
• Descriptive text that describes the extension.
6292
27.2 Warn-Codes
6293
This specification establishes the Warn-codes sub-registry under http://www.iana.org/assignments/sip-parameters
6294
and initiates its population with the warn-codes listed in Section 20.43. Additional warn-codes are registered
6295
by RFC publication.
6296
The descriptive text for the table of warn-codes is:
6297
Warning codes provide information supplemental to the status code in SIP response messages when the
6298
failure of the transaction results from a Session Description Protocol (SDP) (RFC 2327 [1]) problem.
6299
The ”warn-code” consists of three digits. A first digit of ”3” indicates warnings specific to SIP. Until a
6300
future specification describes uses of warn-codes other than 3xx, only 3xx warn-codes may be registered.
6301
Warnings 300 through 329 are reserved for indicating problems with keywords in the session description,
6302
330 through 339 are warnings related to basic network services requested in the session description, 370
6303
through 379 are warnings related to quantitative QoS parameters requested in the session description, and
6304
390 through 399 are miscellaneous warnings that do not fall into one of the above categories.
6305
27.3 Header Field Names
6306
This obsoletes the IANA instructions about the header sub-registry under
http://www.iana.org/assignments/sip-6307
parameters.
6308
The following information needs to be provided in an RFC publication in order to register a new header
6309
field name:
6310
• The RFC number in which the header is registered;
6311
• the name of the header field being registered;
6312
• a compact form version for that header field, if one is defined;
6313
Some common and widely used header fieldsMAYbe assigned one-letter compact forms (Section 7.3.3).
6314
Compact forms can only be assigned after SIP working group review, followed by RFC publication.
6315
27.4 Method and Response Codes
6316
This specification establishes the Method and Response-Code sub- registries under
http://www.iana.org/assignments/sip-6317
parameters and initiates their population as follows. The initial Methods table is:
6318
INVITE [RFCxxxx]
6319
ACK [RFCxxxx]
6320
BYE [RFCxxxx]
6321
CANCEL [RFCxxxx]
6322
REGISTER [RFCxxxx]
6323
OPTIONS [RFCxxxx]
6324
INFO [RFC2976]
6325
The response code table is initially populated from Section 21, the portions labeled Informational,
Suc-6326
cess, Redirection, Client-Error, Server-Error, and Global-Failure. The table has the following format:
6327
Type (e.g. Informational)
6328
Number Default Reason Phrase [RFCxxx]
6329
The following information needs to be provided in an RFC publication in order to register a new response
6330
code or method:
6331
• The RFC number in which the method or response code is registered;
6332
• the number of the response code or name of the method being registered;
6333
• the default reason phrase for that response code, if applicable;
6334
27.5 The “message/sip” MIME type.
6335
This document registers the “message/sip” MIME media type in order to allow SIP messages to be tunneled
6336
as bodies within SIP, primarily for end-to-end security purposes. This media type is defined by the following
6337
information:
6338
Media type name: message
6339
Media subtype name: sip
6340
Required parameters: none
6341
Optional parameters: version
6342
version: The SIP-Version number of the enclosed message
6343
(e.g., "2.0"). If not present, the version defaults to "2.0".
6344
Encoding scheme: SIP messages consist of an 8-bit header optionally
6345
followed by a binary MIME data object. As such, SIP messages
6346
must be treated as binary. Under normal circumstances SIP
6347
messages are transported over binary-capable transports, no
6348
special encodings are needed.
6349
Security considerations: see below
6350
Motivation and examples of this usage as a security mechanism in concert with S/MIME are given
6351
in 23.4.
6352
27.6 New Content-Disposition Parameter Registrations
6353
This document also registers four newContent-Dispositionheader “disposition-types”: alert, icon,
ses-6354
sion and render. The authors request that these values be recorded in the IANA registry for
Content-6355
Dispositions.
6356
Descriptions of these “disposition-types”, including motivation and examples, are given in Section 20.11.
6357
Short descriptions suitable for the IANA registry are:
6358
alert the body is a custom ring tone to alert the user
6359
icon the body is displayed as an icon to the user
6360
render the body should be displayed to the user
6361
session the body describes a communications session, for example,
6362
an RFC2327 SDP body
6363