US Payphones wiki by payphones.telesfor.org

Elcotel 5 / Olympian 5501 board, when initialized, is mostly unusable - majority of numbers cannot be called without programming the rates. Essentially, only 7-digit numbers work with a 25 cent charge.

I found a way to make the phone operate like a regular landline, with the following notes:

• No coin is required to place a call
• Coins deposited are always returned after the call (or always collected if the coin relay connection is reversed)
• Phone generates the iconic coin tones when coins are deposited during a call
• Dialing out is not fully transparent, digits are buffered but any 7, 10 or 11-digit NANP number can be dialed
• Phone rings, and incoming calls can be answered
• Modem answers after the 5th ring and can be programmed

Here's the setup:

1. Restore defaults: on-hook, press and hold the reset button, go off-hook until relay clicks are heard
2. Go off hook, wait for dial tone, dial #99999999
3. Wait 4 seconds
4. Dial 975 *2*. Voice should respond: nine seven five - two
5. Dial 973, hang up.

Phone operates a so called “Bright coin line” mode used as a temporary setup.