For multi-application environments, We also offer an Automatic Ringdown Circuit card.

The 3311R Automatic Ringdown Circuit card enables two telephones to ring one another and communicate. Lifting the handset of one telephone will ring the other until answered or the initiating telephone hangs up. Anytime both telephones are off-hook a talk path is established. A ring back tone is provided to the initiating telephone. Four ring cadences are offered as described below.

The 3311R card is installed in our 3500 Rack mount shelf, which can hold up to 16 cards. Each card maps to a 2 wire pairs on the shelf back planes 25 pair connectors as shown in the attached diagram. T1&R1 are the pair associated with the OH1 light (off-hook one), T2&R2 are associated with the OH2 light (off-hook two).

The 3500 Rack Mount Shelf has wiring accommodation on the back of the unit with 25 pair connectors. Designed for 19" racks the shelf requires 3 mounting spaces and comes with a power supply.