URI
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...
This document defines the URI scheme "tel", which describes resources
identified by telephone numbers. A telephone number ...
... both public and private numbers.)
The termination point of the "tel" URI telephone number is not
restricted. It can be in the public telephone network ...
... including voice, data, and fax. The URI can refer to resources
identified by a telephone number, including but not limited to
...
... telephone call.
The "tel" URI is a globally unique identifier ("name") only; it does
not describe the steps necessary to reach a particular number and
...
... Dial strings are beyond the scope of this document.
Both approaches can be expressed as a URI. For dial strings, this
URI ...
... URI. For dial strings, this
URI is passed to an entity that can reproduce the actions specified
in the dial string ...
... approach is beyond the scope of this specification.
The approach described here has the URI specify the telephone number
as an identifier ...
... services, such as electronic banking or
voicemail, cannot be specified in a "tel" URI.
The notation for phone numbers ...
... 3192draft [RFC3192]. However, the syntax
differs as this document describes URIs whereas RFC 3191draft and RFC 3192draft
...
... 3191draft and RFC 3192draft use "/" to
indicate parameters (qualifiers). Since URIs use the forward slash
to describe path hierarchy, the URI scheme described here uses the
...
... indicate parameters (qualifiers). Since URIs use the forward slash
to describe path hierarchy, the URI scheme described here uses the
semicolon, in keeping with Session Initiation Protocol (SIP ...
... subscriber' part of the
syntax as part of the 'user element' in the SIP URI. Other protocols
may also use this URI scheme.
...
... URI Syntax ...
... 2396(-> 3986std66) [RFC2396], indicating the
actual characters contained in the URI. If the reserved characters
"+", ";", "=", and "?" are used as delimiters between components of
...
... reserved characters
"+", ";", "=", and "?" are used as delimiters between components of
the "tel" URI, they MUST NOT be percent encoded. These characters
MUST be percent encoded if they appear in tel URI parameter values.
...
... the "tel" URI, they MUST NOT be percent encoded. These characters
MUST be percent encoded if they appear in tel URI parameter values.
Characters other than those in the "reserved" and "unsafe" sets (see
...
...
This simplifies comparison when the "tel" URI is compared
character by character, such as in SIP URIs ...
... URI Comparisons ...
...
Two "tel" URIs are equivalent according to the following rules:
o Both must be either a 'local-number ...
... separator' characters.
o Parameters are compared according to 'pname', regardless of the
order they appeared in the URI. If one URI has a parameter name
not found in the other, the two URIs ...
... o Parameters are compared according to 'pname', regardless of the
order they appeared in the URI. If one URI has a parameter name
not found in the other, the two URIs are not equal.
...
... URI. If one URI has a parameter name
not found in the other, the two URIs are not equal.
o URI comparisons are case-insensitive ...
...
All parameter names and values SHOULD use lower-case characters, as
tel URIs may be used within contexts where comparisons are case
sensitive.
...
... The 'telephone-subscriber' part of the URI indicates the number. The
phone number can be represented in either global (E.164 ...
... Phone numbers MAY contain visual separators. Visual separators
('visual-separator') merely aid readability and are not used for URI
comparison or placing a call.
Although it complicates comparisons, this specification retains
...
... 2396(-> 3986std66)
[RFC2396], which remarks that "A URI often needs to be remembered by
people, and it is easier for people to remember a URI when it
...
... RFC2396], which remarks that "A URI often needs to be remembered by
people, and it is easier for people to remember a URI when it
consists of meaningful components". Also, ISBN URNs documented in
...
... space
characters as visual separators in printed telephone numbers, "tel"
URIs MUST NOT use spaces in visual separators to avoid excessive
escaping.
...
... alphabetic characters corresponding to certain numbers on the
telephone keypad. The URI format does not support this notation, as
the mapping from alphabetic characters to digits is not completely
uniform internationally, although there are standards [E.161 ...
... PBX), a state or province, a particular local exchange
carrier, or a particular country. URIs with local phone numbers
should only appear in environments where all local entities ...
... country code
or numbering plan. Recall that "tel" URIs are identifiers; it is
sufficient that a global number is unique, but it is not required
...
... identifiers.
If the recipient of a "tel" URI uses it simply for identification,
the receiver does not need to know anything about the context ...
... descriptor. It simply treats it as one part of a globally unique
identifier, with the other being the local number. If a recipient of
the URI intends to place a call to the local number, it MUST
understand the context and be able to place calls within that
...
... identified with the 'extension' parameter. At most, one of the
'isdn-subaddress' and 'extension' parameters can appear in a "tel"
URI, i.e., they cannot appear both at the same time.
...
...
Future protocol extensions to this URI scheme may add other
parameters ('parameter' in the ABNF). Such parameters can be either
...
... implementation MAY ignore optional parameters and MUST NOT use the
URI if it contains unknown mandatory parameters. The "m-" prefix
...
... number.
Entities that forward protocol requests containing "tel" URIs with
optional parameters MUST NOT delete ...
...
tel:+1-201-555-0123: This URI points to a phone number in the United
States. The hyphens are included to make the number more human
...
...
tel:7042;phone-context=example.com: The URI describes a local phone
number valid within the context ...
... in spirit, it is closer to the URN schemes that also leave the
resolution to an external mechanism. The same "tel" URI may get
translated to any number of other URIs in the process of setting up ...
... resolution to an external mechanism. The same "tel" URI may get
translated to any number of other URIs in the process of setting up
the call.
...
... Signaling protocols such as SIP allow negotiating the call type and
parameters, making the very basic indication within the URI scheme
moot. Also, since the call type can change frequently, any such
indication in a URI ...
... URI scheme
moot. Also, since the call type can change frequently, any such
indication in a URI is likely to be out of date. If such designation
is desired for a device that directly places calls without a
signaling protocol ...
... "tel" was chosen because it is widely recognized that none of the
other suggestions appeared appropriate. "Callto" was discarded
because URI schemes locate a resource and do not specify an action to
be taken. "Telephone" and "phone" were considered too long and not
...
... Usage of Telephone URIs in HTML ...
...
Links using the "tel" URI SHOULD enclose the telephone number so that
users can easily predict the action taken when following the link ...
... On a public HTML page, the telephone number in the URI SHOULD always
be in the global form, even if the text of the link uses some local
...
... SIP can use the "tel" URI anywhere a URI is allowed, for example as a
Request-URI, along with "sip" and "sips" URIs ...
... URI anywhere a URI is allowed, for example as a
Request-URI, along with "sip" and "sips" URIs. For brevity, we will
imply "sips" URIs ...
... URI is allowed, for example as a
Request-URI, along with "sip" and "sips" URIs. For brevity, we will
imply "sips" URIs when talking about SIP ...
... Request-URI, along with "sip" and "sips" URIs. For brevity, we will
imply "sips" URIs when talking about SIP URIs. Both "tel" and SIP ...
... URIs can contain telephone numbers. In SIP URIs, they appear as the
user part, i.e., before the @ symbol (section 19.1.6 in [RFC3261 ...
... UA connects directly to a PSTN gateway, one of the SIP
proxy servers has to translate the "tel" URI to a SIP URI, with the
host ...
... PSTN gateway, one of the SIP
proxy servers has to translate the "tel" URI to a SIP URI, with the
host part of that URI ...
... SIP URI, with the
host part of that URI pointing to a gateway. Typically, the outbound
proxy server, as the first proxy server ...
... performs this translation. A proxy server can translate all "tel"
URIs to the same SIP host name or select a different gateway ...
... routing logic they desire. For local numbers,
the proxy MUST NOT translate "tel" URIs whose contexts it does not
understand.
...
... Effectively, the combination of local number and phone context makes
the "tel" URI globally unique.
Although web pages, vCard ...
... vCard business cards, address books, and
directories can easily contain global "tel" URIs, users on twelve-
button (IP) phones cannot dial such numbers directly and are
...
... dial strings (section
1) are not directly represented by "tel" URIs, as noted. We refer to
the rules that govern the translation of dial strings into SIP ...
... dial strings into SIP and
"tel" URIs, global or local, as the dial plan. Currently,
translations from dial strings to "tel" URIs ...
... URIs, global or local, as the dial plan. Currently,
translations from dial strings to "tel" URIs have to take place in
end systems. Future efforts may provide means to carry dial strings
...
... end systems. Future efforts may provide means to carry dial strings
in a SIP URI, for example, but no such mechanisms exist as of this
writing.
...
... dial strings into SIP or
"tel" URIs. The dial plan can be manually configured or, preferably,
downloaded as part of a device configuration mechanism. (At this
time, there is no standardized mechanism for this.)
...
... 1. The outbound proxy recognizes the domain name in the "tel" or SIP
URI as its local context and can route the request to a gateway ...
... Proxies
receiving a tel URI with a context they do not understand are
obligated to return a 404 (Not Found) status response so that an
...
... Web clients and similar tools MUST NOT use the "tel" URI to place
telephone calls without the explicit consent of the user of that
...
...
o Calls may incur costs.
o The URI may be used to place malicious or annoying calls.
o A call will take the user's phone line off-hook, thus preventing
its use.
...
... HTML links,
as a malicious party may hide the true nature of the URI in the link
text, as in
...
...
"tel" URIs may reveal private information, similar to including phone
numbers as text. However, the presence of the tel: schema identifier
...
...
The specification is syntactically backwards-compatible with the
"tel" URI defined in RFC 2806(-> 3966prop) [RFC2806] but has been completely
...
... network termination points from dial
strings and removes the latter from the purview of "tel" URIs.
Compared to RFC 2806(-> 3966prop) ...
... dial strings, and pause characters have been
removed. The URI syntax now conforms to RFC 2396(-> 3986std66) [RFC2396].
...
... Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifiers (URI): Generic Syntax", RFC 2396(-> 3986std66), August 1998. ...
... Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource Identifiers (URI) Dynamic Delegation Discovery System (DDDS) Application (ENUM ...