Internet Engineering Task Force Adam Roach
Internet Draft Ericsson Inc.
Category: Informational November 2000
Expires May 2001
<draft-roach-voip-ringtone-00.txt>
Ringback tones in SIP-Based Telephony
Status of this Memo
This document is an Internet-Draft and is in full conformance
with all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
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This document is an individual submission to the IETF. Comments
should be directed to the authors.
Abstract
This document describes a mechanism by which an appropriate
ringback tone may be played to the calling party when the called
party's device is alerting. It is written specifcally to address
the case where the Session Initiation Protocol (SIP) is used to
initiate voice-over-IP calls. It also lists ringback
characteristics for several countries.
1. Introduction
In the current PSTN (public switched telephony network), users
expect to hear an appropriate ringback tone when contacting a
node in a foreign network. For example, when placing a call from
the United States to Sweden, a Swedish ringback tone is heard by
the caller.
Further, it is currently possible that calls terminating on a PBX
exchange receive special ringback tones which are distinct from
those used by the PSTN in the country in which the PBX resides.
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In order to ease the transition from standard circuit-switched
telephony to voice-over-IP telephony, it is desirable that, when
feasable, user experience remains largely the same. In the case
of providing an appropriate ringback tone, doing so is quite
trivial.
This document defines two extension headers to SIP [1] to allow
such behavior. The first, "Country," specifies the country in
which the called party is located. The second, "Ringback," allows
the called party to give an specific frequency and cadence for
the ringback tone. Both headers are expected to be included only
in "180 Ringing" responses to "INVITE" requests.
2. Client Handling
If a SIP UAS (called party) wishes to suggest that a specific
ringback tone be played to the calling party, it may include one
or both of the "Country" or "Ringback" headers (defined below) in
its "180 Ringing" responses to "INVITE" requests. For robust
operation, it is strongly recommended that UASs wishing to use
this extension include both headers.
UACs (calling party agents) may elect to implement either or both
of the "Ringback" and "Country" headers (although, for robustness
sake, are encouraged to implement both). Note that low-memory
embedded devices may not have the luxury of storing ringtone
information for scores of countries; similarly, many clients may
choose not to parse out the slightly more complicated "Ringback"
syntax and instead opt to use the "Country" header exclusively.
When a UAC (calling party) understanding either or both of the
"Country" and "Ringback" headers receives them in a "180 Ringing"
message, it can use them to generate an approprite ringback tone
for the calling user. In the case that only a "Country" header is
present, the ringback tone is that defined in section 4. When a
"Ringback" header is present, it will define a specific tone
(frequency and cadence) to be played to the calling user.
In the case that the UAC understands both headers, "Ringback" is
expected to take precedence over "Country." This allows the
definition of custom ringback tones (e.g. for special PBX
ringback).
It is suggested that nodes implementing the extension described
in this document also implement the "Reliability of Provisional
Responses in SIP" extension [6] ; this will ensure delivery of
the "180 Ringing" response.
2.1. New SIP headers
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This table expands on tables 4 and 5 in RFC 2543 [1] .
Header field where proxy ACK BYE CAN INV OPT REG
---------------------------------------------------------
Country 180 - - - o - -
Ringback 180 - - - o - -
2.1.1. SIP "Country" Header
The following SIP header is defined.
Country = "Country" ":" country-code
country-code = 2(lower-case)
lower-case = %x61-7a ; lowercase letters a-z
This header is used to convey which country-specific ringback
tone is to be presented to the calling party. The defined values
for "country-code" and their corresponding ringback tone
definitions are given in section 4.
Note that the "Country" header may be generally useful in other
situations which are outside the scope of this document. Draft
authors are encouraged to reuse the "Country" header where
appropriate. The syntax and accepted values (based on ISO 3166
[3] and the IANA TLD list [2] ) are expected remain the largely
the same, with the possible addition of parameters when needed
(e.g. "Country: gb;subdivision=sct").
2.1.2. SIP "Ringback" Header
The following SIP header is defined.
Ringback = "Ringback" ":" frequency ";" cadence
frequency = 1*DIGIT [("x" | "+") 1*DIGIT]
cadence = duration ";" duration *(";" duration ";" duration)
duration = 1*DIGIT ["." 1*DIGIT]
When present, this header gives a specific definition of the
ringback tone to be played for the calling party.
The "frequency" parameter specifies the tone to be played. All
frequency numbers represent a sine-wave frequency in hertz.
If the frequency paremeter contins a single number, it represents
a pure tone to be played. If a frequency of the format "f1 + f2"
is specified, both frequencies f1 and f2 should be played
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simultaneously to generate the tone. If a frequency of the format
"f1 x f2" is speficied, the frequency f1 should be modulated by
the frequency f2 to generate the tone.
The remaining numbers in the "Ringback" header represent the
cadence at which the tone is to be played. There must always be
an even number of cadence parameters; clients receiving an odd
number of cadence parameters are expected to ignore the
"Ringback" header as malformed. The first cadence parameter is a
decimal duration, in seconds, for which the tone is to be played.
The second parameter is a duration, in seconds, which should be
paused before playing the tone again. Third and subsequent
parameters specify additional on/off periods for the tone. All
ringtone patterns repeat.
2.2. Alternate Handling
If no "Country" or "Ringback" header is present, clients
implementing this extension may choose to make an intellegent
guess about the called party's country.
If the "180 Ringing" message contains a "Contact" header using a
symbolic name (i.e. resolvable by DNS), the client takes note of
the top-level-domain of this contact address for the processing
described below. If the "Contact" header contains an IP address,
the client may attempt to perform a DNS lookup on this IP address
to determine the top-level-domain for its preferred name.
If a top-level-domain could not be determined from the "Contact"
header, the same series of steps is applied to the address in the
"To" header.
If a country-specific top-level-domain can be determined via the
steps above, the client will play the ringtone matching this
country (as if it had been specified in a "Country" header). Note
that the country-specific top-level-domain "uk" should be treated
the same as "gb."
If a non-country-specific top-level-domain is determined, it is
suggested that the client play one of: the ringback tone local to
the calling party, North American ringback tone (see section
4.165. ), or a generic ringback tone meeting the requirements
described in ITU-T E.180 [4] (e.g. 425 Hz at a cadence of 1
second on, 4 seconds off). It would be appropriate to allow the
user to select between these three modes of operation to suit
personal preferences.
3. Proxy Handling
No special proxy handling is required by this extension.
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4. Ringtone Characteristics by Country
This section provides a reference for relevant information about
a number of countries. "Code" is the two-letter "country-code"
token to be used in the "Country:" header. "Frequency" describes
the frequency/frequencies which compose(s) the ringback tone, and
the remaining information describes the cadence of the ringback
tone.
The two-letter country codes in this section are largely aligned
which those published in ISO 3166 [3] , with some minor additions
from the IANA document "Root-Zone Whois Information" [2] for
practical considerations.
The ringback tones and cadences are beleived to be the most
common form of ringback tone in the associated country, as
published in Suppliment 2 to ITU-T E.180 [5] .
4.1. Albania
Code: al
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.2. Algeria
Code: dz
Frequency: 25 Hz
- 1.5 seconds on
- 3.5 seconds off
4.3. Angola
Code: ao
Frequency: 25 Hz
- 1 second on
- 5 seconds off
4.4. Anguilla
Code: ai
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.5. Antigua And Barbuda
Code: ag
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Frequency: 440 Hz
- 2 seconds on
- 4 seconds off
4.6. Argentina
Code: ar
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.7. Aruba
Code: aw
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.8. Ascension
Code: ac
Frequency: 440 Hz
- 1 second on
- 3 seconds off
4.9. Australia
Code: au
Frequency: 400 Hz modulated with 17 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.10. Austria
Code: at
Frequency: 420 Hz
- 1 second on
- 5 seconds off
4.11. Bahamas
Code: bs
Frequency: 400 Hz
- 2 seconds on
- 4 seconds off
4.12. Bahrain
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Code: bh
Frequency: 440 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.13. Barbados
Code: bb
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.14. Belarus
Code: by
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.15. Belgium
Code: be
Frequency: 425 Hz
- 1 second on
- 3 seconds off
4.16. Benin
Code: bj
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.17. Bermuda
Code: bm
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.18. Bhutan
Code: bt
Frequency: 400 Hz + 25 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2.6 seconds off
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4.19. Botswana
Code: bw
Frequency: 400 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.20. Brazil
Code: br
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.21. British Indian Ocean Territory
Code: io
Frequency: 440 Hz
- 1 second on
- 3 seconds off
4.22. British Virgin Islands
Code: vg
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.23. Brunei Darussalam
Code: bn
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.3 seconds off
- 0.4 seconds on
- 2 seconds off
4.24. Bulgaria
Code: bg
Frequency: 425 Hz
- 1 second on
- 9 seconds off
4.25. Burkina Faso
Code: bf
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Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.26. Burundi
Code: bi
Frequency: 425 Hz
- 1.7 seconds on
- 3.3 seconds off
4.27. Cameroon
Code: cm
Frequency: 440 Hz
- 1.7 seconds on
- 3.3 seconds off
4.28. Canada
Code: ca
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.29. Cayman Islands
Code: ky
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.30. Central African Rep.
Code: cf
Frequency: 425 Hz
- 1.7 seconds on
- 3.3 seconds off
4.31. Channel Islands: Jersey
Code: je
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.32. Chile
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Code: cl
Frequency: 400 Hz
- 1 second on
- 3 seconds off
4.33. China
Code: cn
Frequency: 450 Hz
- 1 second on
- 4 seconds off
4.34. Comoros
Code: km
Frequency: 425 Hz
- 1.71 seconds on
- 3.31 seconds off
4.35. Costa Rica
Code: cr
Frequency: 425 Hz
- 1.2 seconds on
- 4.6 seconds off
4.36. Cote D'Ivoire
Code: ci
Frequency: 50 Hz
- 1.66 seconds on
- 3.33 seconds off
4.37. Croatia
Code: hr
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.38. Cuba
Code: cu
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.39. Cyprus
Code: cy
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Frequency: 425 Hz
- 1.5 seconds on
- 3 seconds off
4.40. Czech Rep.
Code: cz
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.41. Denmark
Code: dk
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.42. Djibouti
Code: dj
Frequency: 425 Hz
- 1.5 seconds on
- 3.5 seconds off
4.43. Dominica
Code: dm
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.44. Dominican Rep.
Code: do
Frequency: 400 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2.2 seconds off
4.45. Ecuador
Code: ec
Frequency: 425 Hz
- 1.2 seconds on
- 4.65 seconds off
4.46. Egypt
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Code: eg
Frequency: 425 Hz modulated with 50 Hz
- 2 seconds on
- 1 second off
4.47. El Salvador
Code: sv
Frequency: 425 Hz
- 1.2 seconds on
- 5 seconds off
4.48. Estonia
Code: ee
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.49. Ethiopia
Code: et
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.50. Falkland Islands
Code: fk
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
4.51. Faroe Islands
Code: fo
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.52. Fiji
Code: fj
Frequency: 133 Hz modulated with 16 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.53. Finland
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Code: fi
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.54. France
Code: fr
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.55. French Polynesia
Code: pf
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.56. Gabon
Code: ga
Frequency: 440 Hz
- 1.5 seconds on
- 3 seconds off
4.57. Gambia
Code: gm
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.58. Germany
code: de
Frequency: 425 Hz
- 0.25 seconds on
- 4 seconds off
- 1 second on
- 4 seconds off
- 1 second on
- 4 seconds off
4.59. Ghana
Code: gh
Frequency: 400 Hz
- 1 second on
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- 4 seconds off
4.60. Gibraltar
Code: gi
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.61. Greece
Code: gr
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.62. Greenland
Code: gl
Frequency: 445 Hz
- 1 second on
- 4 seconds off
4.63. Grenada
Code: gd
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.64. Guadeloupe
Code: gp
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.65. Guiana
Code: gf
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.66. Guinea
Code: gn
Frequency: 450 Hz
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- 0.4 seconds on
- 0.2 seconds off
4.67. Guyana
Code: gy
Frequency: 425 Hz
- 1.75 seconds on
- 3.25 seconds off
4.68. Honduras
Code: hn
Frequency: 440 Hz
- 0.5 seconds on
- 4 seconds off
- 2 seconds on
- 4 seconds off
4.69. Hongkong
Code: hk
Frequency: 440 Hz + 480 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 3 seconds off
4.70. Hungary
Code: hu
Frequency: 425 Hz
- 1.2 seconds on
- 3.7 seconds off
4.71. Iceland
Code: is
Frequency: 425 Hz
- 1.2 seconds on
- 4.7 seconds off
4.72. India
Code: in
Frequency: 400 Hz modulated with 25 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2.6 seconds off
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4.73. Indonesia
Code: id
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.74. Iran
Code: ir
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.75. Iraq
Code: iq
Frequency: 400 Hz
- CONTINUOUS
4.76. Ireland
Code: ie
Frequency: 400 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.77. Israel
Code: il
Frequency: 400 Hz
- 1 second on
- 3 seconds off
4.78. Italy
Code: it
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.79. Jamaica
Code: jm
Frequency: 440 Hz modulated with 480 Hz
- 2 seconds on
- 4 seconds off
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4.80. Japan
Code: jp
Frequency: 400 Hz modulated with 16 Hz
- 1 second on
- 2 seconds off
4.81. Jordan
Code: jo
Frequency: 420 Hz modulated with 40 Hz
- 1.2 seconds on
- 4.8 seconds off
4.82. Kenya
Code: ke
Frequency: 425 Hz
- 1 second on
- 4 seconds off
- 1 second on
- 2 seconds off
- 1 second on
- 5 seconds off
- 0.4 seconds on
- 0.2 seconds off
4.83. Kiribati
Code: ki
Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.84. Korea (Democratic People's Republic of)
Code: kp
Frequency: 440 Hz + 480 Hz
- 1 second on
- 2 seconds off
4.85. Korea (Republic of)
Code: kr
Frequency: 440 Hz + 480 Hz
- 1 second on
- 2 seconds off
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4.86. Kuwait
Code: kw
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.87. Kyrgyzstan
Code: kg
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.88. Lao
Code: la
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.89. Lebanon
Code: lb
Frequency: 435 Hz
- 1.2 seconds on
- 4.4 seconds off
4.90. Liberia
Code: lr
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.91. Lithuania
Code: it
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.92. Luxembourg
Code: lu
Frequency: 425 Hz
- 1 second on
- 4 seconds off
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4.93. Macau
Code: mo
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.94. Madagascar
Code: mg
Frequency: 25 Hz
- 1.66 seconds on
- 3.33 seconds off
4.95. Malawi
Code: mw
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.96. Malaysia
Code: my
Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.97. Maldives
Code: mv
Frequency: 400 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.98. Mali
Code: ml
Frequency: 425 Hz
- 1.7 seconds on
- 3.3 seconds off
4.99. Malta
Code: mt
Frequency: 400 Hz + 450 Hz
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- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.100. Martinique
Code: mq
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.101. Mauritania
Code: mr
Frequency: 425 Hz
- 1.5 seconds on
- 3.5 seconds off
4.102. Mauritius
Code: mu
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.103. Mayotte
Code: yt
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.104. Mexico
Code: mx
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.105. Moldova
Code: md
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.106. Montserrat
Code: ms
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Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.107. Morocco
Code: mc
Frequency: 425 Hz
- 1.66 seconds on
- 3.33 seconds off
4.108. Mozambique
Code: mz
Frequency: 400 Hz
- 1 second on
- 5 seconds off
4.109. Namibia
Code: na
Frequency: 400 Hz modulated with 33 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.110. Nauru
Code: nr
Frequency: 400 Hz
- 1 second on
- 4 seconds off
4.111. Nepal
Code: np
Frequency: 425 Hz
- 1.1 seconds on
- 3.1 seconds off
4.112. Netherlands
Code: nl
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.113. New Caledonia
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Code: nc
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.114. New Zealand
Code: nz
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.115. Niger
Code: ne
Frequency: 440 Hz
- 1.7 seconds on
- 3.3 seconds off
4.116. Nigeria
Code: ng
Frequency: 400 Hz
- 2 seconds on
- 4 seconds off
4.117. Norway
Code: no
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.118. Oman
Code: om
Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.119. Pakistan
Code: pk
Frequency: 450 Hz
- 1 second on
- 4 seconds off
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4.120. Panama
Code: pa
Frequency: 425 Hz
- 1.2 seconds on
- 4.65 seconds off
4.121. Papua New Guinea
Code: pg
Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.122. Paraguay
Code: py
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.123. Philippines
Code: ph
Frequency: 450 Hz
- 1 second on
- 10 seconds off
4.124. Poland
Code: pl
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.125. Portugal
Code: pt
Frequency: 400 Hz
- 1 second on
- 5 seconds off
4.126. Qatar
Code: qa
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
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- 0.2 seconds off
- 0.4 seconds on
- 2.2 seconds off
4.127. Reunion
Code: re
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.128. Romania
Code: ro
Frequency: 400 Hz modulated with 16 Hz
- 2 seconds on
- 4 seconds off
4.129. Russia
Code: ru
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.130. Rwanda
Code: rw
Frequency: 440 Hz
- 1.7 seconds on
- 3.3 seconds off
4.131. St Helena
Code: sh
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
4.132. St Kitts And Nevis
Code: kn
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.133. St Lucia
Code: lc
Frequency: 425 Hz
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- 0.375 seconds on
- 0.25 seconds off
- 0.375 seconds on
- 2 seconds off
4.134. St Pierre And Miquelon
Code: pm
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.135. St Vincent And The Grenadines
Code: vc
Frequency: 400 Hz + 450 Hz
- 0.2 seconds on
- 0.4 seconds off
4.136. San Marino
Code: sm
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.137. Sao Tome And Principe
Code: st
Frequency: 425 Hz
- 1 second on
- 5 seconds off
4.138. Saudi Arabia
Code: sa
Frequency: 425 Hz
- 1.2 seconds on
- 4.6 seconds off
4.139. Senegal
Code: sn
Frequency: 400 Hz
- 1.7 seconds on
- 3.3 seconds off
4.140. Seychelles
Code: sc
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Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.141. Sierra Leone
Code: sl
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.142. Singapore
Code: sg
Frequency: 425 Hz modulated with 24 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.143. Slovakia
Code: sk
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.144. Slovenia
Code: si
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.145. Solomon
Code: sb
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
4.146. South Africa
Code: za
Frequency: 400 Hz modulated with 33 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
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- 2 seconds off
4.147. Spain
Code: es
Frequency: 425 Hz
- 1.5 seconds on
- 3 seconds off
4.148. Sri Lanka
Code: lk
Frequency: 425 Hz
- 0.4 seconds on
- 0.2 seconds off
4.149. Suriname
Code: sr
Frequency: 425 Hz
- 15 seconds on
- 0.5 seconds off
4.150. Swaziland
Code: sz
Frequency: 400 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 4 seconds off
4.151. Sweden
Code: se
Frequency: 425 Hz
- 1 second on
- 5 seconds off
4.152. Switzerland
Code: ch
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.153. Syria
Code: sy
Frequency: 425 Hz
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- 1 second on
- 4 seconds off
4.154. Tajikistan
Code: tj
Frequency: 425 Hz
- 0.8 seconds on
- 3.2 seconds off
4.155. Tanzania
Code: tz
Frequency: 400 Hz
- CONTINUOUS
4.156. Thailand
Code: th
Frequency: 400 Hz
- 1 second on
- 4 seconds off
4.157. Trinidad And Tobago
Code: tt
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.158. Tunisia
Code: tn
Frequency: 425 Hz
- 1.2 seconds on
- 4.6 seconds off
4.159. Turkey
Code: tr
Frequency: 450 Hz
- 2 seconds on
- 4 seconds off
4.160. Turkmenistan
Code: tm
Frequency: 25 Hz
- 0.4 seconds on
- 4 seconds off
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4.161. Turks And Caicos Islands
Code: tc
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.162. Uganda
Code: ug
Frequency: 133 Hz + 17 Hz
- 0.25 seconds on
- 0.5 seconds off
- 0.25 seconds on
- 2 seconds off
4.163. United Arab Emirates
Code: ae
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.164. United Kingdom
Code: gb
Frequency: 400 Hz + 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
- 2 seconds off
4.165. United States
Code: us
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.166. United States Virgin Islands
Code: vi
Frequency: 440 Hz + 480 Hz
- 2 seconds on
- 4 seconds off
4.167. Uruguay
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Code: uy
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.168. Vanuatu
Code: vu
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.169. Wallis And Futuna
Code: wf
Frequency: 440 Hz
- 1.5 seconds on
- 3.5 seconds off
4.170. Western Samoa
Code: ws
Frequency: 425 Hz modulated with 25 Hz
- 0.375 seconds on
- 0.25 seconds off
- 0.375 seconds on
- 2 seconds off
4.171. Yugoslavia
Code: yu
Frequency: 450 Hz modulated with 25 Hz
- 1 second on
- 9 seconds off
4.172. Zambia
Code: zm
Frequency: 425 Hz
- 1 second on
- 4 seconds off
4.173. Zimbabwe
Code: zw
Frequency: 400 Hz modulated with 450 Hz
- 0.4 seconds on
- 0.2 seconds off
- 0.4 seconds on
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- 2 seconds off
5. Example Messages
This section provides a collection of SIP messages which
demonstrate the various uses of the "Country:" and "Ringback:"
headers.
5.1. Dual-Tone Ringback
This is an example of how a message might look for a standard
two-tone ringback. In this example, both a country code of "us"
and the standard US ringtone are specified.
SIP/2.0 180 Ringing
To: <sip:adam.roach@ericsson.com>
From: <sip:ake.svensson@ericsson.se>;tag=012345
Call-ID: cmk2109fj@ws17.ericsson.se
CSeq: 397 INVITE
Via: SIP/2.0/UDP fw.ericsson.se
Via: SIP/2.0/UDP ws17.ericsson.se
Country: us
Ringback: 440+480;2;4
Content-Length: 0
5.2. Modulated Ringback
This is almost identical to the previous example, with the
exception that Australian ringback is being provided. This
demonstrates the syntax for modulated ringback tones.
SIP/2.0 180 Ringing
To: <sip:bruce@ericsson.com.au>
From: <sip:adam.roach@ericsson.com>;tag=34789a
Call-ID: 13098jv@b04a24.ericsson.com
CSeq: 32849 INVITE
Via: SIP/2.0/UDP b04a24.ericsson.com
Country: au
Ringback: 400x17;0.4;0.2;0.4;2
Content-Length: 0
5.3. Continuous Ringtone
Some localities provide an continuous ringtone, which indicates
that there is no pause in the tone whatsoever. The suggested
syntax for encoding such a ringtone is to provide an "off" period
of 0.
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SIP/2.0 180 Ringing
To: <sip:sjk@pc.tz>
From: <sip:adam.roach@ericsson.com>;tag=39835afe
Call-ID: ckn9q23k@b04a24.ericsson.com
CSeq: 3249786 INVITE
Via: SIP/2.0/UDP b04a24.ericsson.com
Country: tz
Ringback: 400;1;0
Content-Length: 0
5.4. No "Ringback" specified
This is an example of a message which specifies no particular
ringtone pattern. If the calling party client understands the
country code of "gb," it will provide the proper ringback tone;
otherwise, it will provide default handling.
SIP/2.0 180 Ringing
To: <sip:ebm@company.co.uk>
From: <sip:adam.roach@ericsson.com>;tag=1987
Call-ID: 1358fjslk83la0@b04a24.ericsson.com
CSeq: 985325 INVITE
Via: SIP/2.0/UDP b04a24.ericsson.com
Country: gb
Content-Length: 0
5.5. Special PBX double-ring ringback
This message gives an example in which the default ringtone for
the country should be overridden (e.g. because the call has
terminated on a PBX). The "Country" header is still provided so
that clients not implementing the "Ringback" header can still
provided a regionalised dialtone.
SIP/2.0 180 Ringing
To: <sip:adam.roach@ericsson.com>
From: <sip:ake.svensson@ericsson.se>;tag=012345
Call-ID: cmk2109fj@ws17.ericsson.se
CSeq: 397 INVITE
Via: SIP/2.0/UDP fw.ericsson.se
Via: SIP/2.0/UDP ws17.ericsson.se
Country: us
Ringback: 440+480;0.5;0.5;1;4
Content-Length: 0
5.6. Custom-defined ringback
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This message gives an example in which the specific ringback tone
has been provided, but no country. Clients not implementing the
"Ringback" header will treat this as a normal "Ringing" message.
SIP/2.0 180 Ringing
To: <sip:adam.roach@ericsson.com>
From: <sip:ake.svensson@ericsson.se>;tag=012345
Call-ID: cmk2109fj@ws17.ericsson.se
CSeq: 397 INVITE
Via: SIP/2.0/UDP fw.ericsson.se
Via: SIP/2.0/UDP ws17.ericsson.se
Ringback: 350;0.2;0.2;0.2;4
Content-Length: 0
6. References
[1] M. Handley/H. Schulzrinne/E. Schooler/J. Rosenberg, "SIP:
Session Initiation Protocol", RFC 2543, IETF; March 1999.
[2] "Root-Zone Whois Information,"
http://www.iana.org/cctld/cctld-whois.htm, IANA.
[3] "Codes for the Representation of Names of Countries," ISO
3166, ISO; 1993
[4] "Technical Characteristics of Tones for the Telephone
Service," ITU-T E.180, ITU; 1993
[5] "Various Tones Used in National Networks," ITU-T E.180
Suppliment 2, ITU; January 1994
[6] J. Rosenberg/H. Schulzrinne, "Reliability of Provisional
Responses in SIP," draft-ietf-sip-100rel-02.txt, IETF; June
2000. Work in progress.
7. Security Considerations
Note that user location (including information as broad as
"country") may be considered private information. As such, the
user should have direct control over the presence and value of
the "Country:" header.
8. Author's Address
Adam Roach
Ericsson Inc.
Mailstop L-04
851 International Pkwy.
Richardson, TX 75081
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USA
Phone: +1 972-583-7594
Fax: 972-669-0154
E-Mail: adam.roach@ericsson.com
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