h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Yes, but did all dials operate counterclockwise? Or were they different in some remote part of the world, such as the southern hemisphere?

Hello Gnomon... Interesting read. But I agree there are more mysteries that could be tackled. For your standars this Entry does indeed have an incomplete feel.

Spinks I think mentioned the 'test ping'

My grandma never went to the phone when it was raining, because she was afraid that a lightning could struck the telephone wire somewhere and would electrocute her. She's got a wireless telephone now, but of course you don't get her on the phone when it's raining. The mystery question to me always was... If it is so common that people get electrocuted on the phone during bad weather, how come you never hear of it in the news?

I also agree that including the word 'dial' in the title somewhere might help out.

More assorted stuff:

Why is the 'dial tone' set to 440 Hz?
Is the occupied and ringing signal the same in UK, US, Europe?
How many volts do the telephone companies send through the wires? (can you tap that voltage and load, say a battery for free?)- That voltage is always used by the likes of McGyver and the A-team)
I heard somewhere that doctors can send electric shocks through the phone so it works as a defibrillator. Now I thought that was a bit hard to swallow, but, hey... DO you know something about that?


If you go to tone-dialling phones:

Who invented that standard, what are the involved frequencies?


OK I'll stop here... I guess you will end up re-titling this Entry as it does not deal with all 'telephone mysteries' but rather concentrates on 'why is the emergency number 911 and not 999?'

A very cool read anyways, Gnomon...

HELL

For the record, the dialling motion in Australia was clockwise. Was it actually anti-clockwise elsewhere? Odd.

You 'dial' with the finger clockwise... Actually you're not dialling, you're loading the coil of the dialling mechanism. The dialling itself, the mechanism, works automatically counterclockwise... Or have I missed something?

HELL

Ah. I knew there was a reason I stayed out of discussions about mechanical things. Hell, that makes sense - and what I said doesn't. Please disregard it, everyone.

My dial phone broke down about 10 years ago, and I can't now remember which way it went.

I agree that this entry should not be "Every single mystery of the telephone explained", but I'll see can I add something about the electrical processes involved.

Sure Gnomon. Nobody is ever going to be able to elucidate all mysteries of the telephone.

But I think you could add some more 'mysteries' and not 'just' the explanation as to why the emergency numbers are 999, 911 or 112.

Including the working mechanism of a telephone would give the Entry a different spin, IMO.

HELL

A thought occurs. This would be a good Entry to show my pupils when they don't understand my 'dictaphone' joke...

B

It *was* clockwise! At least here in the states.

Like Hell said, you 'dialled' clockwise, but you were just loading the dialler which would send the signal after the dial was released and spinning counter-clockwise.

When push-button phones first started appearing, weren't the signals still sent as pulses? Wasn't it awhile before there was true 'touch-tone' dialling? I remember cheapie push-button phones used to have a switch between pulse and tone, and tone dialling used to be a premium feature of phone companies that you had to pay extra for.

And then there's the retro-style phones with the buttons arranged around a 'dial' so they just look like old phones. I HATE those!

I remember trying to 'speed-dial' numbers on the rotary and getting wrong numbers because the dial wasn't getting all the way around

>> When push-button phones first started appearing, weren't the signals still sent as pulses? <<

This is true. I still have and old pulse dial push button phone. British Telecom still accommodates pulse dialling along with tone dialling. I can't use it though because my modem reacts to the pulses and goes into auto answer mode and I end up talking to myself.

Donald

Technical question?

1. Do modern telephones use moving coil, capacitative or piezo-electric microphones?

2. Do modern telephones use moving coil, capacitative or piezo-electric ear-piece speakers?

1) Yes
2) Yes

Mostly they are both capacitative - moving coil tends to be too large for ideal. Piezoelectrics are still in their infancy, but are used in some modern models.

B

I don't think that line testing is a mystery of the telephone: most people never even know that it happens.

Zube

It does explain the Unix command 'ping', though.

Here's a little more detail about 911:

'Friday, Jan. 12, 1968 AT&T announces their designation of 911 as a universal emergency number at a press conference in the Washington (DC) office of Indiana Rep. Ed Roush, who had championed for Congressional support for "one number." AT&T's plan affected only the Bell companies, and not any of the independent telephone companies. Up to this point, the number "911" wasn't mentioned in any literature, and apparently wasn't identified until the press conference. In fact, a Wall Street Journal article written the day before the press conference didn't mention "911" as the number that AT&T selected.'

http://www.911dispatch.com/911_file/history/911history.html

There is, however a bit of misleading information on the above linked page. It says that Canada went to 911 in 1972, but, in fact, '1969
The first "911" system in Canada introduced.' http://about.telus.com/careers/history.html In Edmonton, Alberta: 'Mar. 9, 1969: Edmonton becomes the first Canadian city to join the North American Universal Emergency Telephone No. 911 plan.' http://www.edmonton2004.com/comm_firsts.html

I've added a few new sections:

Tone Dialling
Ringing
Voice
Communication

I've also added the bit about the satisfaction of slamming down the handset. But I now need a concluding remark to end if on a lighter note. Any suggestions?

How about that voltage in the telephone lines? It always intrigued me, as it is used in movies n'such...

apart from that
HELL

I'll see what I can do. And I forgot to put in the Cognitive Psychology bit about which ear to use.

All this work has elevated it from an OK Entry to an excellent Entry.

B