Telephone, technical question.

[Callithrix]

Hi, on the contact page of the British Antarctic Survey's website, the telephone number has a clickable link to a audio file of the dialling tone of their phone number, which, if played with the phone reciever held to your PC speaker, would cause the phone to automatically dial the telephone number for you. It's clever stuff, how does it do that?

[spacechimp]

I don't think that's true, ^^.

[spacechimp]

Maybe if you have a particular type of phone.

[Callithrix]

I just found out that it's called a DTMF (dual-tone multi-frequency) and the tone in question is at:
www.antarctica.ac.uk/About_BAS/Cambridge/Contact/index.php

[rojash]

All modern "tone dial" phones use DTMF dialling, which is to say that your telephone generates a specific pair of notes for each number to be dialled. Obviously, the notes don't have to be generated by the phone and can be transmitted by p[laying them into the mouthpiece. I don't know if it's still available, but there used to be a gadget like a PDA that you could store all your phone numbers in, then when you were out, you could use it with any phone to autodial, simply by holding it to the mouthpiece and pushing a button.