Avaya Nortel Communication Server 1000 Reference page 395

Operation
Dial pulses or DTMF tones are then presented from the CO. When the called party answers,
the universal trunk card reverses battery and ground on the tip and ring leads to the CO. The
trunk is arranged for first party release. The CO releases the trunk by removing the low-
resistance loop, at which time normal battery and ground are restored at the near-end. This
also applies to incoming tie trunk calls from a far-end PBX.
Note:
The near-end can be configured for immediate start, delay dial, or wink start.
Circuit Card Reference July 2011 395