Whoa! That takes me back to the mid-60’s when we found a way of getting free calls from ‘phone boxes.

By tapping out the number on the bar on the telephone cradle you could get connected for free. You had to tap the number with a pause between numbers and the numbers ‘0’ and ‘9’ could be dialled.

Does that ring any bells? – although it used to ring a few numbers!

We didn’t think ourselves as ‘phreaks’ though.

Hugh                                                                                                      Amadeal Ltd

Old phone boxes used to have a coin mech that generated 10pps “dial pulses” to indicate the coin type.  In order to discriminate between these and normal pulses the line was reversed in “quiescent” mode and series diodes used in the payphone to decide which of the dial or mech was in circuit.  Once a valid coin had been signalled the exchange would reverse the line back to normal to permit dialling and speech.  I knew of at least one payphone in a university hall of residence where enterprising engineers had shorted out the dial diode so the coin value could be “dialed in”.  Ah, those were the days before hacking became a thing.  I recall that Plessey had a “consulting vandal” they used to try to break payphones too.

On 20 August 2025 at 09:54 Hugh Stewart-Smith 1 Said:

Whoa! That takes me back to the mid-60’s when we found a way of getting free calls from ‘phone boxes.

By tapping out the number on the bar on the telephone cradle you could get connected for free. You had to tap the number with a pause between numbers and the numbers ‘0’ and ‘9’ could be dialled.

Does that ring any bells? – although it used to ring a few numbers!

We didn’t think ourselves as ‘phreaks’ though.

Hugh                                                                                                      Amadeal Ltd

Yes, I remember that from my university days in the sixties.  You could also make long distance calls by stringing together dialing codes to get from one exchange to another.  If you went through too many exchanges to reach your destination the call quality became only just intelligible.  The exchanges used electro-mechanical switches called uniselectors which advanced one step for each pulse you sent.

Russell

The other game was to string together a load of dialling codes to ring the phone at the neighbouring desk in the same office.  “We made our own entertainment in those days…”