RFC 3891
The Session Initiation Protocol (SIP) "Replaces" Header
RFC 3891: The Session Initiation Protocol (SIP) "Replaces" Header 💖
Okay bestie, this is RFC 3891 and it's giving Standards Track 🎀. It was written by R. Mahy (of Cisco Systems, Inc.), B. Biggs, and R. Dean, and it dropped in September 2004. The header doesn't list any RFCs that it obsoletes or updates, so this one stands on its own 🦋.
Status of this Memo 📝
This document is an Internet standards track protocol for the Internet community, and it's asking for discussion and suggestions for improvements 🌸. For the standardization state and status of this protocol, check the current edition of the "Internet Official Protocol Standards" (STD 1). Distribution of this memo is unlimited ✨.
Copyright Notice ©️
Copyright (C) The Internet Society (2004) 💜.
Abstract 🦋
Okay so this document defines a brand-new header for Session Initiation Protocol (SIP) multi-party apps and call control 🎀. The Replaces header is used to logically replace an existing SIP dialog with a new SIP dialog, and that's literally the whole vibe 💅. This primitive can power a bunch of features, like "Attended Transfer" and "Call Pickup" 🔥. Note that the definition of these example features is non-normative, so they're just examples and not rules 🙈.
Table of Contents 📑
1. Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. User Agent Server Behavior: Receiving a Replaces Header . . . 4
4. User Agent Client Behavior: Sending a Replaces Header . . . . 6
5. Proxy Behavior. . . . . . . . . . . . . . . . . . . . . . . . 7
6. Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. The Replaces Header . . . . . . . . . . . . . . . . . . 7
6.2. New Option Tag for Require and Supported Headers. . . . 8
7. Usage Examples. . . . . . . . . . . . . . . . . . . . . . . . 9
7.1. Replacing an Early Dialog at the Originator . . . . . . 9
8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9.1. Registration of "Replaces" SIP Header . . . . . . . . . 13
9.2. Registration of "replaces" SIP Option-tag . . . . . . . 13
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
11. References. . . . . . . . . . . . . . . . . . . . . . . . . . 13
11.1. Normative References. . . . . . . . . . . . . . . . . . 13
11.2. Informative References. . . . . . . . . . . . . . . . . 14
12. Authors' Addresses. . . . . . . . . . . . . . . . . . . . . . 15
13. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 161. Overview ✨
This document describes a SIP [1] extension header field that's part of the SIP multiparty applications architecture framework [10] 🧚. The Replaces header is used to logically replace an existing SIP dialog with a new SIP dialog, and it's especially useful in peer-to-peer call control environments 👑.
One big use of the "Replaces" header is swapping one participant for another in a multimedia conversation 💖. Yes, this is already possible with 3rd party call control [11] (3pcc), but that model needs a central point of control, and that's not always wanted. So a way to do the same call control primitives in a distributed, peer-to-peer way is super desirable 😭.
The authors chose to use a new INVITE with a new header for dialog matching, instead of making implicit associations in an incoming INVITE based on call-id or other fields. Here's why 💅:
- An INVITE already has the correct semantics for a new call 🌈
- Using an explicit Replaces header in a new request makes the intent of the request obvious 🔥
- A unique call-id may be given to the replacement call, which avoids dialog matching problems in any of the related User Agents ✨
- There are no adverse effects if the header is unsupported 🫶
The Replaces header enables services like attended call transfer, retrieve from park, and going from a locally mixed conference to a two-party call, all in a distributed peer-to-peer way 🦋. That list isn't exhaustive, btw. Even though the Replaces header is often used together with the REFER [8] method in a Transfer [12], the two can also be used independently 🍓.
Here's an example. Alice is talking to Bob from phone1 📞. She transfers Bob to a Parking Place while she goes to the lab 🌸. When she gets there, she retrieves the "parked" call from phone2 by sending an INVITE with a Replaces header field to Bob, using the dialog information Bob shared with the Parking Place. Alice got that info through some out-of-band mechanism. Maybe she subscribed to it from the Parking Place (using the session dialog package [13]), or maybe she went to a website and clicked on a URI 💻. Here's a short call flow for the example. (Via and Max-Forwards headers are omitted for clarity, so don't panic if they're missing 🙈.)
Alice Alice Parking
phone1 phone2 Bob Place
| | | |
|<===============================>| |
| | | |
| Alice transfers Bob to Parking Place |
| | | |
|------------REFER/200----------->| *1 *2 |
|<--NOTIFY/200 (trying)-----------|--INVITE/200/ACK-->|
|<--NOTIFY/200 (success)----------|<=================>|
|------------BYE/200------------->| |
| | | |
| | | |
| Alice later retrieves call from another phone |
| | | |
| *3 |-INV w/Replaces->| |
| |<--200-----------| |
| |---ACK---------->|----BYE/200------->|
| |<===============>| |
| | | |Message *1: Bob-> Parking Place
INVITE sip:parkingplace@example.org SIP/2.0
To: <sip:parkingplace@example.org>
From: <sip:bob@example.org>;tag=7743
Call-ID: 425928@bobster.example.org
CSeq: 1 INVITE
Contact: <sip:bob@bobster.example.org>
Referred-By: <sip:alice@phone1.example.org>Message *2: Parking Place -> Bob
SIP/2.0 200 OK
To: <sip:parkingplace@example.org>;tag=6472
From: <sip:bob@example.org>;tag=7743
Call-ID: 425928@bobster.example.org
CSeq: 1 INVITE
Contact: <sip:parkplace@monopoly.example.org>Message *3: Alice@phone2 -> Bob
INVITE sip:bob@bobster.example.org
To: <sip:bob@example.org>
From: <sip:alice@phone2.example.org>;tag=8983
Call-ID: 09870@phone2.example.org
CSeq: 1 INVITE
Contact: <sip:alice@phone2.example.org>
Require: replaces
Replaces: 425928@bobster.example.org;to-tag=7743;from-tag=64722. Conventions 💅
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14, RFC 2119 [2] 🎀.
This document keeps coming back to the terms "confirmed dialog" and "early dialog" 🔁. Both are defined in Section 12 of SIP [1] 💖.
That's the end of Part 1, babes 🌈✨
3. User Agent Server Behavior: Receiving a Replaces Header ✨
Okay so when an INVITE with a Replaces header shows up, the User Agent (UA) goes hunting for a match 🔍 It checks the call-id, to-tag, and from-tag against a confirmed or early dialog. The User Agent Server (UAS) compares the to-tag and from-tag parameters as if they were tags in an incoming request. So the to-tag gets checked against the local tag, and the from-tag gets checked against the remote tag. Lowkey genius 💅
If there's more than one Replaces header field in an INVITE, or a Replaces header field in any request that isn't an INVITE, the UAS MUST reject the request with a 400 Bad Request response. ❌ Not it, bestie.
The Replaces header has its own specific call control semantics 🎀 If a Replaces header field and another header field with contradictory semantics both show up in the same request, the request MUST be rejected with a 400 "Bad Request" response. 🙅♀️
If the Replaces header field matches more than one dialog, the UA MUST act as if no match is found. 🤷♀️
If there's no match, the UAS rejects the INVITE and returns a 481 Call/Transaction Does Not Exist response. Same energy if the Replaces header field matches a dialog that wasn't created with an INVITE: the UAS MUST reject the request with a 481 response. 💀
If the Replaces header field matches a dialog that has already terminated, the UA SHOULD decline the request with a 603 Declined response. (If the matched invitation was just terminated, the replacement request should fail as well. Declining with a 600-class response prevents an irritating race condition where the UA rings or alerts for a replacement call nobody wants. 🙄)
If the Replaces header field matches an active dialog, the UA MUST verify that the initiator of the new INVITE is authorized to replace the matched dialog. 🔐 If the initiator has been successfully authenticated as equivalent to the user being replaced, the replacement is authorized. For example, if the user being replaced and the initiator share the same credentials for Digest authentication [6], or they sign the replacement request with S/MIME [7] using the same private key and present the (same) corresponding certificate used in the original dialog, then the replacement is authorized. 🫶
Alternatively, the Referred-By mechanism [4] gives the UAS another way to check that a replacement request was sent on behalf of the other participant in the matched dialog (in this case, triggered by a REFER request). If the replacement request contains a Referred-By header that corresponds to the user being replaced, the UA SHOULD treat the replacement as if the replaced party authorized it. The Referred-By header SHOULD reference a corresponding, valid Refererred-By Authenticated Identity Body [5]. 📎
The UA MAY apply other local policy to authorize the rest of the request. In other words, the UAS may apply a different policy to the replacement dialog than the one it applied to the replaced dialog. 🧚
The UA MAY also use other authorization mechanisms defined for this purpose in standards track extensions. Extensions could define other mechanisms for transitively asserting authorization of a replacement. 🌈
If authorization succeeds, the UA attempts to accept the new INVITE, reassign the user interface and other resources of the matched dialog to the new INVITE, and shut down the replaced dialog. 👑 If the UA cannot accept the new INVITE (for example, it cannot establish required QoS or keying, or it has incompatible media), the UA MUST return an appropriate error response and MUST leave the matched dialog unchanged. 🙈
If the Replaces header field matches a confirmed dialog, the UAS checks for the presence of the "early-only" flag in the Replaces header field. (This flag lets the UAC avoid a potentially undesirable race condition, described in Section 7.1.) If the flag is present, the UA rejects the request with a 486 Busy response. Otherwise, it accepts the new INVITE by sending a 200-class response, and shuts down the replaced dialog by sending a BYE. 📞
If the Replaces header field matches an early dialog that the UA initiated, it accepts the new INVITE by sending a 200-class response, and shuts down the replaced dialog by sending a CANCEL. ✨
If the Replaces header field matches an early dialog that this UA did not initiate, it returns a 481 (Call/Transaction Does Not Exist) response to the new INVITE and leaves the matched dialog unchanged. Note that since Replaces matches only a single dialog, the replacement dialog won't be retargeted using the same forking logic as the original request that created the early dialog. 🦋
(Currently, no use cases have been identified for replacing just a single dialog in this circumstance.) 🤔
4. User Agent Client Behavior: Sending a Replaces Header 💖
A User Agent that wants to replace a single existing early or confirmed dialog with a new dialog of its own MAY send the target User Agent an INVITE request containing a Replaces header field. 📨 The User Agent Client (UAC) puts the Call-ID, to-tag, and from-tag information for the target dialog into a single Replaces header field, then sends the new INVITE to the target. If the user agent only wants to replace an early dialog (like in the Call Pickup example in Section 7.1), the UAC MAY also include the "early-only" parameter in the Replaces header field. A UAC MUST NOT send an INVITE with a Replaces header field that tries to replace an early dialog not originated by the target of that INVITE. 🚫
Note that this mechanism can't match multiple dialogs, can't match an entire call or an entire transaction, and can't follow a chain of proxy forking logic. 🙅♀️ For example, if Alice replaces Cathy in an early dialog with Bob, but Bob doesn't answer, Alice's replacement request won't match other dialogs Bob's UA redirects to, or other branches his proxy forwards to. Although this specification takes reasonable precautions against unexpected behavior when forking happens, implementations SHOULD only address replacement requests (i.e., set the Request-URI of the replacement request) to the SIP Contact URI of the target. 🎯
5. Proxy behavior 🛣️
Proxy Servers don't need any new behavior to support this extension. 💁♀️ They simply pass the Replaces header field through transparently, as described in the SIP specification.
Note that a proxy (especially one forking based on application layer logic, like caller screening or time-of-day routing) could forward an INVITE containing a Replaces header field to a completely unrelated set of Contacts, not the original request it was meant to replace. 😬 In that case, the INVITE with the Replaces header field will fail.
6. Syntax 📝
6.1. The Replaces Header 🎀
The Replaces header field says that a single dialog identified by the header field is to be shut down and logically replaced by the incoming INVITE that contains it. 💅 It's a request header only, and it's defined only for INVITE requests. The Replaces header field MAY be encrypted as part of end-to-end encryption. Only a single Replaces header field value may be present in a SIP request.
This document adds the following entry to Table 2 of [1]. Additions to this table are also provided for extension methods defined at the time of publication of this document. This is provided as a courtesy to the reader and is not normative in any way. MESSAGE, SUBSCRIBE and NOTIFY, REFER, INFO, UPDATE, PRACK, and PUBLISH are defined respectively in [15], [16], [8], [17], [18], [19], and [20].
Header field where proxy ACK BYE CAN INV OPT REG MSG
------------ ----- ----- --- --- --- --- --- --- ---
Replaces R - - - o - - -
SUB NOT REF INF UPD PRA PUB
--- --- --- --- --- --- ---
Replaces R - - - - - - -The following syntax uses the augmented Backus-Naur Form (BNF) as described in RFC 2234 [3]. It relies on a number of productions from SIP [1]. 🧩
Replaces = "Replaces" HCOLON callid *(SEMI replaces-param)
replaces-param = to-tag / from-tag / early-flag / generic-param
to-tag = "to-tag" EQUAL token
from-tag = "from-tag" EQUAL token
early-flag = "early-only"A Replaces header field MUST contain exactly one to-tag and exactly one from-tag, since they're required for unique dialog matching. 🔑 For compatibility with dialogs initiated by RFC 2543 [9] compliant UAs, a tag of zero matches both tags of zero and null. 🧠 A Replaces header field MAY contain the early-flag. ✨
Examples:
Replaces: 98732@sip.example.com
;from-tag=r33th4x0r
;to-tag=ff87ff
Replaces: 12adf2f34456gs5;to-tag=12345;from-tag=54321;early-only
Replaces: 87134@171.161.34.23;to-tag=24796;from-tag=06.2. New Option Tag for Require and Supported Headers 🏷️
This specification defines a new Require/Supported header option tag, "replaces". UAs that support the Replaces header MUST include the "replaces" option tag in a Supported header field. 🙌 UAs that want explicit failure notification if Replaces isn't supported MAY include the "replaces" option in a Require header field.
Example:
Require: replaces, 100rel7. Usage Examples 🎬
The following non-normative examples aren't meant to list every possible way to use this extension. They're more like examples or ideas to get you going. 💡 For more examples, check out SIP Service Examples [14]. Via and Max-Forwards headers are left out for clarity and brevity. 🌸
7.1. Replacing an Early Dialog at the Originator
okay bestie, picture this 🎀 Bob just rolled into the lab and he has NOT registered there yet 💅. His desk phone starts ringing and he's like "wait, that's me!" So he quickly logs into a software UA on a nearby computer. The software UA can see the dialog state of his desk phone, which is giving main character energy 👑. When it notices the phone is ringing, it offers him the choice of taking the call right there. So the software UA sends an INVITE with Replaces to Alice. When Alice's UA gets this new INVITE, it CANCELs her original INVITE and connects Alice to Bob 🦋
Bob Bob
Alice desk lab
| | |
*1 |-----INVITE----------->| |
*2 |<----180---------------| Bob hears desk phone |
| | ringing from lab but |
| | isn't REGISTERed yet |
| | |
| |<--fetch dialog state --|
| |---response ----------->|
*3/4 |<-----INVITE with Replaces/200/ACK--------------|
*5/6 |------CANCEL/200------>| |
*7 |<-----487--------------| |
|------ACK------------->| |
| | |
| | |Message *1: Alice -> Bob's desk phone
INVITE sip:bob@example.org SIP/2.0
To: <sip:bob@example.org>
From: <sip:alice@example.org>;tag=7743
Call-ID: 425928@phone.example.org
CSeq: 1 INVITE
Contact: <sip:alice@phone.example.org>Message *2: Bob's desk phone -> Alice
SIP/2.0 180 Ringing
To: <sip:bob@example.org>;tag=6472
From: <sip:alice@example.org>;tag=7743
Call-ID: 425928@phone.example.org
CSeq: 1 INVITE
Contact: <sip:bob@bobster.example.org>Message *3: Bob in lab -> Alice
INVITE sip:alice@phone.example.org
To: <sip:alice@example.org>
From: <sip:bob@example.org>;tag=8983
Call-ID: 09870@labpc.example.org
CSeq: 1 INVITE
Contact: <sip:bob@labpc.example.org>
Replaces: 425928@phone.example.org
;to-tag=7743;from-tag=6472;early-onlyMessage *4: Alice -> Bob in lab
SIP/2.0 200 OK
To: <sip:alice@example.org>;tag=9232
From: <sip:bob@example.org>;tag=8983
Call-ID: 09870@labpc.example.org
CSeq: 1 INVITE
Contact: <sip:alice@phone.example.org>Message *5: Alice -> Bob's desk
CANCEL sip:bob@example.org SIP/2.0
To: <sip:bob@example.org>
From: <sip:alice@example.org>;tag=7743
Call-ID: 425928@phone.example.org
CSeq: 1 CANCEL
Contact: <sip:alice@phone.example.org>Message *6: Bob's desk -> Alice
SIP/2.0 200 OK
To: <sip:bob@example.org>
From: <sip:alice@example.org>;tag=7743
Call-ID: 425928@phone.example.org
CSeq: 1 CANCEL
Contact: <sip:bob@bobster.example.org>Message *7: Bob's desk -> Alice
SIP/2.0 487 Request Terminated
To: <sip:bob@example.org>;tag=6472
From: <sip:alice@example.org>;tag=7743
Call-ID: 425928@phone.example.org
CSeq: 1 INVITE8. Security Considerations 🔥
okay this section is SERIOUS, so pay attention 🙈 The extension in this doc totally changes how secure SIP devices are. Right now in SIP, even if an eavesdropper learns the Call-ID, To, and From headers of a dialog, they can't easily modify or destroy that dialog as long as Digest authentication or end-to-end message integrity is being used.
This extension can be used to disconnect participants or swap them out of a multimedia conversation. So invitations with the Replaces header MUST only be accepted if the peer asking for the replacement has been properly authenticated with a standard SIP mechanism (Digest or S/MIME), and is authorized to request a replacement of the target dialog. All SIP implementations are already required to support Digest Authentication. On top of that, implementations that support the Replaces header SHOULD also implement the Referred-By mechanism 💀
How a User Agent figures out which requests are legitimately allowed to replace dialogs is not simple at all. It depends on a lot of local policy configuration. In general, there are four cases where authorizing a replacement is reasonable or warranted:
- Replacement made by a party considered equivalent to the replaced party
- Replacement made on behalf of the replaced party (perhaps transitively)
- Replacement made by a former participant
- Replacement made by a specifically authorized party
Starting with #1 as an example: if an executive and an assistant both receive requests for a shared address-of-record, and that's how it's configured, either one should be able to replace the other's dialogs for the shared identity 🫶 They could even share the same keying material (Digest or S/MIME), or one could hold an authorization document signed by the other that expresses this relationship. Likewise, in a call center, each agent could hold credentials that supervisors also have access to.
The most common use of a replacement is at the request of the replaced participant, who no longer wants to be involved. This is the case in lots of features, like completing an Attended Transfer or turning a 3-way call into a point-to-point call. These replacements are typically triggered by a REFER [8] request from the replaced participant. The Referred-By [4] mechanism defines one way to identify the apparent original requester, and it can point to a SIP Authenticated Identity Body [5] (an S/MIME-based signed assertion) to lock this info down 🔒
In the example in section 1, Alice sends an INVITE with Replaces to Bob. Alice was a former participant in the conversation and had a previous dialog relationship with Bob. Alice can use the same Digest or S/MIME credentials she used to authenticate with Bob during the original call to prove she was a former participant. Note that this justification for replacing calls is more dangerous than the others, and in most cases it's just another way of saying the replacing participant is available. Implementations SHOULD NOT rely on this method as an authorization mechanism 🙅♀️
The last scenario is the easiest to secure but the least likely to be useful in practice. It's unlikely that some random host on the Internet knows about any special authorization relationship between the replaced and replacing parties. However, this use case may be useful in some environments. Since this usage does not effectively degrade the security of the solution, it is still allowed.
Some ways of getting the dialog information needed by the Replaces header (Call-ID, to-tag, and from-tag) include URIs on a web page, subscriptions to an appropriate event package, and notifications after a REFER request. Since messing with this dialog information could cause User Agents to replace the wrong dialog, message integrity protection for this information is STRONGLY RECOMMENDED. Using end-to-end security mechanisms to encrypt this information is also RECOMMENDED 🌸
This extension was designed to take advantage of future signature or authorization schemes defined in standards track extensions. In general, call control features benefit a LOT from that kind of work ✨
9. IANA Considerations
9.1. Registration of "Replaces" SIP header
Name of Header: Replaces
Short form: none
Normative description: section 6.1 of this document9.2. Registration of "replaces" SIP Option-tag
Name of option: replaces
Description: Support for the SIP Replaces header
SIP headers defined: Replaces
Normative description: This document10. Acknowledgments
Big thanks to Robert Sparks, Alan Johnston, Dan Petrie, Ben Campbell, and lots of other members of the SIP WG for their continued support of distributed call control in SIP 💜🫶
11. References
11.1. Normative References
- [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002.
- [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997.
- [3] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997.
- [4] Sparks, R., "The Session Initiation Protocol (SIP) Referred-By Mechanism", RFC 3892, September 2004.
- [5] Peterson, J., "The Session Initiation Protocol (SIP) Authenticated Identity Body (AIB) Format", RFC 3893, September 2004.
- [6] Franks, J., Hallam-Baker, P., Hostetler, J., Lawrence, S., Leach, P., Luotonen, A., and L. Stewart, "HTTP Authentication: Basic and Digest Access Authentication", RFC 2617, June 1999.
- [7] Ramsdell, B., "Secure/Multipurpose Internet Mail Extensions (S/MIME) Version 3.1 Message Specification", RFC 3851, July 2004.
11.2. Informative References
- [8] Sparks, R., "The Session Initiation Protocol (SIP) Refer Method", RFC 3515, April 2003.
- [9] Handley, M., Schulzrinne, H., Schooler, E., and J. Rosenberg, "SIP: Session Initiation Protocol", RFC 2543, March 1999.
- [10] Mahy, R., "A Call Control and Multi-party usage framework for the Session Initiation Protocol (SIP)", Work in Progress, March 2003.
- [11] Rosenberg, J., Peterson, J., Schulzrinne, H., and G. Camarillo, "Best Current Practices for Third Party Call Control (3pcc) in the Session Initiation Protocol (SIP)", BCP 85, RFC 3725, April 2004.
- [12] Sparks, R. and A. Johnston, "Session Initiation Protocol Call Control - Transfer", Work in Progress, February 2003.
- [13] Rosenberg, J. and H. Schulzrinne, "An INVITE Initiated Dialog Event Package for the Session Initiation Protocol (SIP)", Work in Progress, March 2003.
- [14] Johnston, A. and S. Donovan, "Session Initiation Protocol Service Examples", Work in Progress, March 2003.
- [15] Campbell, B., Rosenberg, J., Schulzrinne, H., Huitema, C., and D. Gurle, "Session Initiation Protocol (SIP) Extension for Instant Messaging", RFC 3428, December 2002.
- [16] Roach, A., "Session Initiation Protocol (SIP)-Specific Event Notification", RFC 3265, June 2002.
- [17] Donovan, S., "The SIP INFO Method", RFC 2976, October 2000.
- [18] Rosenberg, J., "The Session Initiation Protocol (SIP) UPDATE Method", RFC 3311, October 2002.
- [19] Rosenberg, J. and H. Schulzrinne, "Reliability of Provisional Responses in Session Initiation Protocol (SIP)", RFC 3262, June 2002.
- [20] Campbell, B., "SIMPLE Presence Publication Mechanism", Work in Progress, February 2003.
12. Authors' Addresses
Rohan Mahy Cisco Systems, Inc. 5617 Scotts Valley Dr Scotts Valley, CA 95066 USA
EMail: rohan@cisco.com
Billy Biggs
EMail: bbiggs@dumbterm.net
Rick Dean
EMail: rfc@fdd.com
13. Full Copyright Statement ✨
Okay bestie, the legal bit 💅 Copyright (C) The Internet Society (2004). 🎀
This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 💖
This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/S HE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 🫶
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