Network Working Group G. Parsons Request for Comments: 3804 Nortel Networks Category: Standards Track June 2004
Voice Profile for Internet Mail (VPIM) Addressing
Status of this Memo
This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2004).
This document lists the various Voice Profile for Internet Mail (VPIM) email address formats that are currently in common use and defines several new address formats for special case usage. Requirements are imposed on the formats of addresses used in VPIM submission mode.
This document lists the various VPIM email address formats that are currently in common use and defines several new address formats for special case usage. Requirements are imposed on the formats of addresses used in VPIM submission mode
[VPIM2] does not place any restrictions on the email address format. However, it does recommend the use of a numeric LHS since many legacy voice mail systems only use digits to identify mailboxes. Further, it recommends a structure to handle private, international and extensions. The private format has become deployed in most existing VPIM v2 systems, further some systems will only accept messages from addresses with a numeric LHS.
[IVM] does not describe addressing at all. The LHS format is left to the discretion of the mailbox owner. However, it is useful in some cases (like submission or tunneling) to specify a LHS format. A format based on GSTN addressing [GSTN] is presented.
This document defines the various recipient (i.e., TO) addresses for VPIM and IVM messages.
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 RFC 2119 [RFC2119].
"LHS" as used in this document is to be interpreted as the left side of the "@" in an email address. It is defined as "local-part" in RFC-2822.
"RHS" as used in this document is to be interpreted as the right side of the "@" in an email address. It is defined as "domain" in RFC- 2822.
VPIM places no restrictions on the form of the Internet address. VPIM systems must be capable of receiving an arbitrary email address and generating a reply to that address. No inferences about the structure of the local part (LHS) should be necessary.
Recipients email addresses must be created in a form compatible with the recipients system and consistent with the address entry capabilities of a telephone user interface.
The following sections use formal syntax compliant with RFC 2234, "Augmented BNF for Syntax Specifications: ABNF".
A gateway translates between dissimilar environments. For VPIM, a gateway connects between the VPIM profile of Internet mail and other voice mail networking protocols (including voice call answer and delivery). These may be proprietary or standard (like AMIS [AMIS- A]). VPIM gateways typically service multiple voice mail users or, in the case of call answer, service only one. In the former case, they serve as a classic "mail transfer agent" (MTA) and in the latter as a classic "mail user agent" (UA).
An onramp is a gateway which connects from another voice mail networking protocol to VPIM. An offramp is a gateway which connects from VPIM to another voice mail networking protocol. Behavior of onramps and offramps is out of scope for this specification.
This specification describes the VPIM service portion of onramp and offramp addressing.
Limited capability voice mail machines may send messages by default to an external message submission gateway. These gateways will convert the unresolved telephone number of the recipient into a
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legitimate email address. Messages requiring address resolution must be sent to a submission system which will convert the submitted address into the route-able email address.
Additionally, limited capability email systems may send messages to a VPIM onramp system indicated on the RHS. The LHS would indicate that the message is to be sent as a VPIM message to the telephone number indicated. In this case, address and message translation is performed by the gateway.
Telephone numbers sent in a VPIM submission mode MUST be sent in one of the following forms.
This is based on the format defined in [GSTN-ADDR] and extensions in [GSTN].
dl-addr-spec = "/DL=" sub-addr ;note that "/DL=" is case INSENSITIVE ext-addr-spec = [ ext-sep sub-addr ] ext-sep = ( "/EXT=" / "+" ) ; note that "/EXT=" is case INSENSITIVE ; "+" is used for compatibility with current ; VPIM v2 addressing
For clarity, here is an example of a very simple vpim-mbox:
The extension syntax, that is a phone number followed by "/EXT=" defining the extension, would be used where the mailbox does not have a direct dial number associated with it (e.g., typically behind a non-ISDN PBX). For example:
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The distribution list syntax, that is a phone number followed by "/DL=" defining the list, would be used to refer to a distribution list associated with the phone number (with or without an extension). For example:
For voice messages that are intended to be sent as AMIS (Audio Messaging Interchange Specification) voice mail messages (as defined in [AMIS-A] and [AMIS-D]), the service-selector element is defined to be:
amis-service-selector = "AMIS"
The resultant amis-address and amis-mbox are formally
amis-address = amis-mbox
amis-mbox = "AMIS=" amis-mailbox [ "/SYSNUM=" amis-sysnum ] ; note that "/SYSNUM=" is case INSENSITIVE
amis-mailbox = ( amis-a / amis-d )
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RFC 3804 VPIM Addressing June 2004
amis-a = amis-a-number
amis-d = [ amis-mailbox-numberplan ][ "+" ] amis-mailbox-id [ "+" ] [ amis-mailbox-extension ] ; The "+" separators are used to be compatible ; the X.400 AMIS-D mailbox definition -- ; if more than one element is present, both ; "+" must appear. Note also that the total ; length of this field is restricted to 32 ; characters by AMIS-D.
amis-PSTN-number = int-country-code "+" area-code "+" local-number "+" ; This is in agreement with ITU [E.164] ; specification and per [AMIS-A] - the ; maximum length is 15 numeric digits. ; The "+" separators are used to be ; compatible with the X.400 AMIS-D ; mailbox definition and replace the '#' ; separators of AMIS-A
amis-private-number = "0++" local-number "+" ; [AMIS-A] indicates that maximum permitted ; length of the private number is 14 ; digits
int-country-code = 1*4(DIGIT)
area-code = 1*(DIGIT)
local-number = 1*(DIGIT)
For more clarity, here is an example of a simple AMIS-A amis-mbox:
Based on [GSTN-ADDR], these are the resultant email addresses for the LHS presented above. VPIM and IVM systems that support submission MUST accept, translate (if necessary), and forward messages sent to these addresses.
Most security considerations are already identified in [VPIM2] and [IVM].
An additional concern would be that the sender must trust and also be aware of the policies of the submission MTA to which the message is submitted. This is because, that MTA will make the determination of where the final destination is and how it will be delivered based on the VPIM submission LHS.
Submission MTAs should take care to not blindly place outdial calls to any number submitted (e.g., international numbers or "1-900" numbers). Ideally, senders should be authenticated to confirm their outdialing privileges.
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