Viking GLS-12 - ground loop converter

Model GLS-12 is designed to allow up to 12 standard telephone sets, multi-line key systems or other loop start equipment to be connected to and operate on two-wire ground start CO trunk lines. The GLS-12 provides the CO ground start line with the signalling required to draw dial tone when the loop start equipment goes off-hook. Incoming calls are not affected by the GLS-12 and ring directly to the loop start devices.