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Old style UK phone to ring


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This document ITU VARIOUS TONES USED IN NATIONAL NETWORKS (ACCORDING TO ITU-T RECOMMENDATION E.180)(03/1998) should clarify ring tones ?

United Kingdom of Great Britain and Northern Ireland FREQUENCY in HZ               CADENCE in seconds
Busy tone -                                           400                          0.375 on 0.375 off
Congestion tone -                                     400                          0.4 on 0.35 off 0.225 on 0.525 off
Dial tone -                                           50//350+440                  continuous
Number unobtainable tone -                            400                          continuous
Pay tone -                                            400                          0.125 on 0.125 off
Payphone recognition tone -                           1200/800                     0.2 on 0.2 off 0.2 on 2.0 off
Ringing tone -                                        400+450//400x25//400x 16 2/3 0.4 on 0.2 off 0.4 on 2.0 off

Cannot seem to format columns.


Those are the tones heard by the caller. Ringing current is a different beast entirely.


P.S. to format columns in a fixed width font just enclose the text in [ code ] & [ /code ] tags (after removing the spaces).

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The frequency was derived from a mains driven motor-generator, the ringer output being 1/3 of the input frequency. This was chosen as being close to the nominal 17 Hz of a manual ringer which all the bell systems were tuned for, and the subscribers accustomed to.




I never came across a mains powered ringing machine in a telephone exchange (that doesn't mean they didn't exist) and I had never heard of 1/3rd of mains frequency before.


I joined P.O. telecoms in 1972 as an apprentice and spent over 20 years of the next 22 working in a selection of telephone exchanges from UAX12 through 2000/4000 Strowger, crossbar to TXE2 & 4 and system X


There were many ways of generating the ringing current and the various tones and I find all the comments so far slightly amusing. Yes there are supposedly standards for correct frequencies and timings but in reality there was considerable variation.


The early vibrator packs or relays for example were influenced by temperature and ringing current frequency could easily vary by +/-50% between a hot day and cold night, anywhere between say 10Hz and 30Hz was common.


There were usually 2 ringer machines, typically of the type in the you tube clip, with auto changeover, listening to the busy tone of both of them (officially 400Hz) commonly demonstrated a significant difference, even thought the machines were running at the right speed according to the tuning fork strobe.


Realistically the public don't know what it should be and they are accustomed to their local exchange, when it 'sounds funny' it usually goes unnoticed.





I have supplied several bits of kit over the years for stage phones, the latest ironically was a recording of a real telephone bell on an ipod and amplified with a 100v amplifier to ring the telephone on stage as the other poster has suggested.


I find the real timing of a ringing phone often sounds too slow for stage work and I speed it up by possibly 25%. That brings 4 cycles down from 10 seconds to 7.5. The American films tend to use a 1:1 timing rather than the 1:2


Definitely disconnect the earpiece, I've seen several shows where the actors has suffered with the unexpected next ringing burst in their ear.


I have also seen an Iphone laying beside the prop phone and it's been rung for the effect but the timing is uncontrollable.


Of course going back to the hand generators there was no control over the speed of the operators hand.


A retired GPO engineer friend (yes really GPO and not BT!) told me that the frequency was changed to 20Hz when ring tone cadence was introduced. The ring tone was electronically generated rather mechanically and 400mS on period is 8 full cycles of 20Hz compared to 6.666667 cycles of 16.66667Hz.



I think he told you wrong, but it may have been the case in his exchange.


The type of machine in the you tube clip is mechanical, one end of the motor is a gearbox and spring contacts giving the timing, the other end of the motor is a series of generators producing the tones, 400, 350, 450 and ringing. I have known this to be 16.67, 20 or 25 depending on the model of ringing machine. these types of machine were introduced at the time of automation and certainly still in use well beyond 1994 when I moved out and for what it's worth many of them were sold on to 3rd world at retirement in UK.





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  • 1 year later...
Much easier to play a 25Hz (20Hz for US) sine wave from your audio cueing package of choice, and feed it into the phone via a power amp.

As mentioned in previous poste the ringing has historically been anything from 10 to 40Hz but is (was?) generally more like 15 to 20HZ. Individual exchanges were plain simply different depending on the 'ringing machine' in use and the state of calibration.

Practical application on stage is not critical as some of the audience are used to 15HZ and others to 25Hz. If you're ringing a classic bell, whichever frequency you go for will sound correct for some and acceptable for others, electronic sounders are so varied that any frequency will do the job, including 50Hz.

Whichever method you use to generate the ringing current, I'd suggest investigating the way that the ringing is tripped in real life(DC supply and a relay) to prevent a very loud burst of ringing in the actors ear from the earpiece or to disconnect the earpiece. This is a big benefit of the item listed above in that it trips the ringing when the phone is lifted and will not ring again until the button is pressed again.

Some of these devices can be operated via DMX, be aware some makes will restart as the DMX channel is refreshed while faded down, worth checking with manufacturer if that's the case with these.

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Thanks for the detail on those aspects sunray.

Last month I modified a phone such that I could ring the bell on one circuit (interrupted by the handset switch), and play audio to the headset on another circuit.Quite easy on big old mechanical phones, probably more complex on a more modern phone.

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Thanks for the detail on those aspects sunray.

Last month I modified a phone such that I could ring the bell on one circuit (interrupted by the handset switch), and play audio to the headset on another circuit.Quite easy on big old mechanical phones, probably more complex on a more modern phone.

Oh yes the old phones were so so versatile. My earliest live telephone call into a PA system was done that way with a modified SM58 mic insert in the handset.
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You are correct and I can only apologies for my poor etiquette :-)

Although I am retired, I used to be a senior software engineer (worked for British Telecom in the UK and the US for 32 years) I am now retired and restore and sell British vintage telephones for interest more than money. Over the years many people have asked me for a simple plug and play telephone intercom solution for less than £100. I could never find one so I developed this solution using "off the shelf VOIP hardware" aka a Grandstream HT502 :-)


The whole point of my solution is to make it VERY simple plug and play, with no need for VOIP, software or electrical skills and to make if for less than £90. However if people have the time (it took me about 1 man month of effort, over 12 months) and the right skills they could probably make this for around £60 in hardware and cables.

Regards & apologies again.


Hi, welcome to Blue Room, we consider it polite if you are advertising your own product to say so. It would be fine to say "I've designed a phone ringer and you can see my video here:".

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