MULTI-PHONE RECORDING DEVICE - $10 (Nashville, Tennessee)

Sold by Radio Shack.
For any recorder with a remote jack.
Stops/starts recording automatically.
Works for all phones on the line.
Enables you to automatically record important phone calls whenever you pick up any phone in your home that shares a line.
No batteries or AC power are required.
Plugs into a standard wall jack.
Has a play/record switch.
Instructions are included.
Ours was never used and is in excellent cosmetic and functional condition.