The Broadcast Tools STA III provides an interface between telephone line and user equipment. The STA III provides a self-null hybrid with balanced input and outputs. The STA III monitors the telephone line for CPC calling party control and long dial tone hang up signals, allowing use behind PBX telephone switches and POTS lines. 
 
Main Features:
•Auto-answer and auto-disconnect via CPC (calling party control) and/or long dial tone hang up signals, allowing use behind PBX telephone switches and POTS lines.
•Front panel, plus remote line seize and drop control for manual operation.
•Remote line busy input.
•Electronic telephone hybrid.
•Remote controllable send and receive audio switcher.
•Balanced bridging audio input with automatic signal limiter with front panel level control.
•Balanced low Z audio output with front panel level control.
•Front panel LEDs display power, ring, valid DTMF tone.
•Two remote controllable SPST relays.
•External hook relay activates when a valid access code is accepted.
•Momentary SPST relay for End Of Call.
•User programmable number of rings before auto-answer.
•User programmable up to ten-digit access code, if required.
•User defeatable beep tones on line seize.
•All connections via screw terminals.
•Loop-thru jack. (This is where you would connect your business telephone system if you were sharing the line.)
•The STA-III's attractive painted metal chassis may be set on a desktop, mounted on a wall or as part of the new optional RA-1 rack shelf for mounting up to three units in 1-RU.