Cisco SIP IP Administrator Guide, Version 7.5
Compliance with RFC 3261
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Compliance with RFC 3261

Table Of Contents

Compliance with RFC 3261

SIP Functions

SIP Methods

SIP Responses

1xx Response—Information Responses

2xx Response—Successful Responses

3xx Response—Redirection Responses

4xx Response—Request Failure Responses

5xx Response—Server Failure Responses

6xx Response—Global Responses

SIP Header Fields

SIP Session Description Protocol Usage

Transport Layer Protocols

SIP Security Authentication

SIP DNS Records Usage

SIP DTMF Digit Transport


Compliance with RFC 3261


This appendix describes how the Cisco IP Phone 7960G/7940G complies with the IETF definition of SIP as described in RFC 3261. It contains compliance information on the following:

SIP Functions

SIP Methods

SIP Responses

SIP Header Fields

SIP Session Description Protocol Usage

Transport Layer Protocols

SIP Security Authentication

SIP DNS Records Usage

SIP DTMF Digit Transport

SIP Functions

Function
Supported?

User agent client (UAC)

Yes

User agent server (UAS)

Yes

Proxy server

Third-party only

Redirect server

Third-party only


SIP Methods

Method
Supported?
Comments

INVITE

Yes

The phone supports midcall changes such as putting a call on hold as signaled by a new INVITE that contains an existing call ID.

ACK

Yes

OPTIONS

Response only

BYE

Yes

CANCEL

Yes

REGISTER

Yes

The phone supports both user and device registration.

REFER

Yes

NOTIFY

Yes

Used for REFER and remote reboot.

UPDATE

Yes

Used for display updates only (SDP updates are not supported).


SIP Responses

The Cisco IP Phone 7960G/7940G supports the following SIP responses:

1xx Response—Information Responses

2xx Response—Successful Responses

3xx Response—Redirection Responses

4xx Response—Request Failure Responses

5xx Response—Server Failure Responses

6xx Response—Global Responses


Note A SIP response that cannot be constructed properly because of a syntactically incorrect received request will be ignored.

A syntactically incorrect response to a sent request will be ignored.


1xx Response—Information Responses

1 xx Response
Supported?
Comments

100 Trying

Yes

The phone generates this response for an incoming INVITE. Upon receiving this response, the phone waits for a 180 Ringing, 183 Session Progress, or 200 OK response.

180 Ringing

Yes

181 Call Is Being Forwarded

See comments

The phone does not generate these responses; however, the phone does receive them. The phone processes these responses in the same way that it processes the 100 Trying response.

182 Queued

183 Session Progress

The phone does not generate this message. Upon receiving this response, the phone provides early media cut-through and then waits for a 200 OK response.


2xx Response—Successful Responses

2 xx Response
Supported?
Comments

200 OK

Yes

202 Accepted

Yes


3xx Response—Redirection Responses

3 xx Response
Supported?
Comments

300 Multiple Choices

Yes

301 Moved Permanently

Yes

302 Moved Temporarily

Yes

The phone generates this response when local call forwarding is enabled. Upon receiving this response, the phone sends an INVITE that contains the contact information received in the 302 Moved Temporarily response.

305 Use Proxy

Yes

The phone does not generate these responses. The phone contacts the new address in the Contact header field.

380 Alternate Service

Yes


4xx Response—Request Failure Responses

4 xx Response
Supported?
Comments

400 Bad Request

Yes

The phone generates a 400 Bad Request response for an erroneous request. For an incoming response, the phone initiates a graceful call disconnect (during which the caller hears a fast busy tone).

401 Unauthorized

Yes

If a 401 Unauthorized response is received, the phone accepts the response and sends a new request that contains the user's authentication information in the format of the HTTP digest as modified by RFC 3261.

402 Payment Required

Yes

The phone does not generate the 402 Payment Required response.

403 Forbidden

Yes

If the phone receives a 403 Forbidden response, it notifies the user of the response. This response indicates that the SIP server has the request but will not provide service.

404 Not Found

Yes

The phone generates this response if it is unable to locate the callee. Upon receiving this response, the phone notifies the user.

405 Method Not Allowed

Yes

If the phone receives a 405 Method Not Allowed response, it notifies the user of the response.

406 Not Acceptable

Yes

The phone does not generate a 406 Not Acceptable response. For an incoming response, the phone initiates a graceful call disconnect (during which the caller hears a busy or fast busy tone) before clearing the call request.

407 Proxy Authentication Required

Yes

If a 407 Proxy Authorization Required response is received, the phone accepts the response and sends a new request that contains the user's authentication information in the format of the HTTP digest as modified by RFC 3261.

408 Request Timeout

Yes

For an incoming response, the phone initiates a graceful call disconnect (during which a caller hears a fast busy). The phone generates this response after an INVITE Expires timeout to avoid leaving the phone in a continuous ringing state (fail safe mechanism). This will occur only if the phone does not receive any messages from the network to tear down the call after the timer expires.

409 Conflict

Yes

The 409 Conflict response indicates that the INVITE request could not be processed because of a conflict with the current state of the resource. If this response is received, the user is notified.

410 Gone

Yes

The 410 Gone response indicates that a resource is no longer available at the server and no forwarding address is known.

411 Length Required

Yes

This response indicates that the user refuses to accept the request without a defined content length. If received, the phone resends the INVITE request if it can add a valid Content-Length header field.

413 Request Entity Too Large

Yes

If a retry-after header field is contained in this response, the user can attempt the call once again in the retry time provided.

414 Request—URL Too Long

Yes

The user is notified if this response is received.

415 Unsupported Media

Yes

The user is notified if this response is received.

420 Bad Extension

Yes

The user is notified if this response is received.

If the phone does not understand the protocol extension specified in the Require field, the 420 Bad Extension response is generated.

480 Temporarily Unavailable

Yes

The response is received only by the phone. The user is notified if this response is received.

481 Call Leg/Transaction Does Not Exist

Yes

The user is notified if this response is received.

482 Loop Detected

483 Too Many Hops

484 Address Incomplete

485 Ambiguous

Yes

If a new contact is received, the phone might reinitiate the call.

486 Busy Here

Yes

The phone generates this response if the called party is off-hook and the call cannot be presented as a call-waiting call. Upon receiving this response, the phone notifies the user and generates a busy tone.

487 Request Canceled

Yes

This response indicates that the initial request is terminated with a BYE or CANCEL request.

488 Not Acceptable

Yes

When media cannot be negotiated properly, the phone receives and generates this response.

491 Request Pending

Yes

Indicates a glare condition (when INVITE requests cross). The phone supports sending and receiving this response.


5xx Response—Server Failure Responses

5 xx Response
Supported?
Comments

500 Internal Server Error

Yes

The phone initiates a graceful call disconnect, and the user is notified.

501 Not Implemented

Yes

502 Bad Gateway

Yes

503 Service Unavailable

Yes

504 Gateway Timeout

Yes

505 Version Not Supported

Yes


6xx Response—Global Responses

6 xx Response
Supported?
Comments

600 Busy Everywhere

Yes

The phone initiates a graceful call disconnect, and the user is notified.

603 Decline

Yes

604 Does Not Exist Anywhere

Yes

606 Not Acceptable

Yes


SIP Header Fields

Header Field
Supported?

Accept

Yes

Accept-Encoding

Yes

Accept-Language

Yes

Alert-Info

Yes

Allow

Yes

Also

Yes

Authorization

Yes

Call-ID

Yes

Call-Info

Yes

CC-Diversion

Yes

CC-Redirect

Yes

Contact

Yes

Content-Disposition

Yes

Content-Encoding

Yes

Content-Length

Yes

Content-Type

Yes

Cseq

Yes

Date

Yes

Diversion

Yes

Encryption

No

Expires

Yes

Event

Yes

From

Yes

Hide

No

Max-Forwards

Yes

Mime-Version

Yes

Organization

No

Priority

No

Proxy-Authenticate

Yes

Proxy-Authorization

Yes

Proxy-Require

Yes

Record-Route

Yes

Referred-By

Yes

Refer-To

Yes

Remote-Party-ID

Yes

Note The Screen parameter is ignored on received Remote-Party-ID and is always set to Yes in sent Remote-Party-ID

Replaces

Yes

Requested-By

Yes

Require

Yes

Response-Key

No

Retry-After

Yes

Route

Yes

RTP-RxStat

Yes

RTP-TxStat

Yes

Server

Yes

Subject

No

Supported

Yes

Timestamp

Yes

To

Yes

Unsupported

Yes

User-Agent

Yes

Via

Yes

Warning

Yes

WWW-Authenticate

Yes


SIP Session Description Protocol Usage

SDP Headers
Supported?

v—Protocol version

Yes

o—Owner or creator and session identifier

Yes

s—Session name

Yes

t—Time description

Yes

c—Connection information

Yes

m—Media name and transport address

Yes

a—Media attribute lines

Yes


Transport Layer Protocols

Protocol
Supported?

Unicast UDP

Yes

Multicast UDP

No

TCP

No


SIP Security Authentication

Basic Authentication
Supported?

Digest Authentication

Yes

Proxy Authentication

No

PGP

No


SIP DNS Records Usage

DNS Resource Record Type
Supported?

Type A

Yes

Type SRV

Yes

NAPTR

No


SIP DTMF Digit Transport

Transport Type
Supported?

RFC 2833

Yes

In-band tones

Yes