[bluepilot]

There were a lot of phone card collectors once upon a time. The international company I worked for had some special ones manufactured which could be used in more than one country. I don't know how they worked but one I had could be used both in Germany and the Netherlands. They were very sought after among the collectors.

Cards were more valuable to collectors if the credit hadn't been used. (Obvious I suppose). I remember someone worked out how to recharge them, or at least ones with a particular chip in them, and for a while there was a booming market in used cards.

I thought it was a great invention when payphones started taking credit cards. No hassle with having the right coins or trying to find somewhere to buy a phone card. I vaguely remember Mercury phones took credit cards and BT ones didn't.