Trunk signaling
A hunt group always has its own extension. Therefore, a caller with a telephone on Communication Manager can dial that extension to call the hunt group. If a trunk group can pass digits from the central office (CO) to Communication Manager, for example, over a DS1 trunk group, a caller can also dial a 7-digit number. The 7-digit number consists of a specified prefix and the extension of the hunt group.
If a trunk group cannot pass digits from the CO to Communication Manager, the system can connect incoming calls to a hunt group only if the trunk group has the hunt group extension as the primary destination. This requirement includes trunk groups for incoming listed directory number (LDN) calls, international exchange calls, 800 service calls, and automatic tie-trunk calls.