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Versions: 00

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
     other groups may also distribute working documents as
     Internet-Drafts.

     Internet-Drafts are draft documents valid for a maximum of six
     months and may be updated, replaced, or obsoleted by other
     documents at any time. It is inappropriate to use Internet-Drafts
     as reference material or cite them other than as "work in
     progress".

     The list of current Internet-Drafts can be accessed at
     http://www.ietf.org/ietf/lid-abstracts.txt

     The list of Internet-Draft Shadow Directories can be accessed at
     http://www.ietf.org/shadow.html

     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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