The TRE-2 is a tone remote encoder that offers the 40 ms F1, F2, and monitor function tones. The function tones are preceded by a 120 ms high-level guard tone at 2175 Hz and followed by a 2175 Hz low-level continuous guard tone. It also offers F3-F10 when a keypad is adapted to the TRE-2.

• Converts DC remotes into Tone remotes
• Modify Telco Butt/In test sets for tone remote