Saturday, 16 October 2010

UK Dial and Progress Tones

Telephone Tones

There are several different telephone tones used in the UK, to indicate busy, call waiting, voicemail etc. These tones are described below.

Sipura Codes

The Cisco / Sipura telephone adaptors have the capability of being programmed to use similar tones. The strings are in the following format, with ring pattern1 being played first, and if present, it is followed with ring pattern 2:
frequency list; ring pattern1 [; ring pattern 2 ...]

frequency list is in the format: f1@l1 [,f2@l2 ...]
ring pattern is in the format: t1(dr1/ds1/x1 [,dr2/ds2/x2])

f - frequency in Hz
l - level in dBm for tone
t - duration of pattern in seconds (* is unlimited)
dr - duration of tone in seconds (* is unlimited)
ds - duration of silence in seconds (* is unlimited)
x - frequency to which this sequence applies (i.e. 1=f1, 2=f2, 1+2=f1&f2)


A description of the BT / UK tones is given below.

Dial Tone (Proceed Indication)

Indicates that the user can now dial.

Continuous tone of 350Hz at -20dB modulated with 440Hz at -23dB.

Sipura Format (Dial Tone): 350@-20,440@-23; 10(*/0/1+2)

Interrupted Dial Tone (Special Proceed Indication)

Used to indicate that add-on services are active, e.g. voicemail.

350Hz pulsing tone with 750ms on at -20dB and off for 750ms, modulated with 440Hz continuous tone at -23dB

Sipura Format (MW1 Dial Tone): 350@-20,440@-23;10(.75/.75/1+2)

Busy Tone (Engaged Tone)

Indicates that the end user line is busy.

Continually pulsing on for 375ms and off for 375ms of 400Hz at -20dB.

Sipura Format (Busy Tone): 400@-20; 10(0.375/0.375/1)

Congestion Tone (Path Engaged Tone)

Indicates routing equipment is temporarily unavailable.

400Hz tone pulsing 400ms on at -20dB, off for 350ms, on for 225ms at -14db, off for 525ms.

Sipura Format:

Number Unobtainable (Connection not Admitted)

Indicates that call cannot be routed to the requested number.

Continuous 400Hz tone at -20dB

Sipura Format (Reorder Tone): 400@-20;10(*/0/1)

Ringing Tone (Awaiting Answer)

Indicates that customer line is being rung.

400Hz tone modulated with 450Hz, continually pulsing on for 400ms at -20dB, off for 200ms, on for 400ms at -20dB and off for 2000ms,

Sipura Format: N/A (produced by telephone network)

Call Waiting Indication

Indicates a second incomming call

400Hz tone at -20dB, on for 100ms, off for 2 seconds.

Sipura Frequency (CWT frequency): 400@-20
Sipura Interval (CWT1 cadence): 30(.1/2)
Sipura Interval (CWT2 cadence): 30(.25/.25,.25/.25,.25/5)


Sipura Format (SIT1 Tone): 950@-16,1400@-16,1800@-16;20(.330/0/1,.330/0/2,.330/0/3,0/1/0)

Disconnected Tone

Sipura Format: 400@-30,400@-30; 2(3/0/1+2)
Sipura Format: 400@-30,400@-30; 2(*/0/1+2)

Ring Styles

This is the standard BT ring

Ring for 60 seconds, 400ms ring, 200ms pause, 400ms ring, 2000ms pause.

Sipura Format (Ring 1 cadence): 60(.4/.2/.4/2)

BT Call Sign

This ring is used for the BT call sign service, which is where a second phone number is provided for the same phone, and the ring tone can be used to differentiate which number has been called.

Ring for 60 seconds, 1000ms ring, 2000ms pause.

Sipura Format (Ring 2 cadence): 60(1/2)

BT Ring Back

This is the ring pattern for the BT ring-back service, i.e. if the number is busy, and you select ring back, the phone will ring with the following pattern.

Ring for 60 seconds, 250ms ring, 250ms pause, 250ms ring, 250ms pause, 250ms ring, 1750ms pause.

Sipura Format (Ring 3 cadence): 60(.25/.25,.25/.25,.25/1.75)

References and Interesting Document

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