And if you dialed T, I, M, you could listen to the speaking clock for freeIn the Cubs, you used to earn part of your Tenderfoot badge by being able to make a successful phone call using these phones. If I remember correctly you put tuppence in and this allowed you to dial then when person answered you pressed button B.
Got me thinking now what button A was for.
Edit. I now know as you dialled and pressed button A when answered. Button B got you your money back if nobody picked up.