ground start

A signaling technique typically used between PBXs and central office switches. Ground start signaling momentarily grounds one side (usually the tip rather than the ring side) of the circuit, sending an immediate signal to the central office switch in order to start, i.e., seize, the trunk and get dial tone. Ground start is superior to loop start as it avoids glare, or collisions between incoming and outgoing calls. Loop start is used in POTS applications between central offices and telephone sets or key telephone systems. See also glare, loop start, and tip and ring.