Useful Information

Baud Rates

Modem type used: V.23 aka 1200/75 7,e,1 (7 data bits, EVEN parity, and one stop bit - as opposed to the usual 8,N,1)

Your modem will be able to recognise this, as it usually auto-trains when you send "AT" to it.

Dial up

Can't get your Prestel Terminal to dial up, because your cheap PABX doesn't support pulse dial?

Of course if you can't do this, you'll need a double adapter and dial the number beforehand and then pick up on the terminal, and hang up the telephone when the modem answers.