The CPC-1 will generate a CPC disconnect signal on a PABX analog station (or any other line that does not provide this signal).
A CPC (Calling Party Control) signal is a momentary break in phone line loop current which is used to signal automated telco equipment (ie. voice mail call sequencers etc.) the distant party has hung up. Central Office telephone lines typically provide this signal but Analog PABX stations do not.
The CPC-1 will generate a 1 second disconnect when it detects a busy signal reorder tones (fast busy) return to dial tone or silence.

Tandem PABX configuration (Redcom etc.).

Analog PABX station to Trunk talk paths between two PABXs.

C.O. lines that don’t provide CPC.

Voice Mail behind PABX.

Add CPC disconnect signal to T-1 channel bank lines.

Call sequencers behind PABX.

ISDN.

VOIP.

Phone line powered (no AC needed).

Return to dial tone (programmable).

Busy signal.

Reorder (fast busy).

Steady silence (programmable).

In use.

Audio detected.

Generated CPC signal.

Caller ID compatible.

Power: Telephone line powered (20VDC 20mA minimum).

Dimensions: 74mm x 53mm x 25mm (2.9″ x 2.1″ x 1.0″).

Environmental: 0° C to 32° C (32° F to 90° F) with 5% to 95% non-condensing humidity.

CPC Disconnect Time: 1 second nominal.

Connections: 4 position screw terminal block.