3) Can I still set this up to take coins? All the equipment is still in the phone including the relay.
It might be possible to do this, actually. However, it would require some experience with electronics to do this! First you would have to know the voltage of the relay, the number of states it has controlling the coinbox and coin inserts and the pinout for it. Next you would have to set up some kind of audio regonition or switch regonition when a nickel, dime, or coin is deposited and connect that to a PC. Then, you would then need to connect the dial to the device (or make the input regonize audio touch-tones when initially dialed and delay them from going on the real phone line. Based on the number one dials, you could then feed an audio signal into the handset speaker to tell the user "Please deposit X dollars and Y cents for Z minutes". Then, you could then read the coin inputs to make sure that is deposited and then connect the handset to the phone line, make it dial the number, listen for a connection and start the timer. The coin relay should then make the coins go into the slot after the call is connected, or when the person hangs up or just before needing to deposit additional coins.
When the timer gets low, the system should play an audio message to "Please deposit X dollars and Y cents for an additional Z minutes" Then, it should open the relay for depositing again and acccept the additional coins. Give the user 20 seconds or so to deposit the coins, and if deposited extend the timer, and if the 20 seconds up, disconnect the line.
It seems like that what you would need to do this is:
* Decoder for phone # touch-tones
* Touch tone dialer tones
* Pre-recorded audio of coin deposit instructions
* Audio mixer that supports phone line audio and computer audio
* Audio of "Please deposit" tones [Some Available from
http://www.thisisarecording.com/pay_phone_deposit_required.html ]
* Interface for the coin relay voltage and amperage that can be controlled by a PC
* Interface for thethe coin mechanism to distinguish coins
This would take a fair amount of work to write the programming for this, but I think it could be done.