H.323 trunks use an ITU-T IP standard for LAN-based multimedia telephone systems. When IP-connected trunks are used, trunk groups can be defined as tie lines equivalent to ISDN-PRI between switches over an IP network.

H.323 trunk groups can be configured as:

• Tie trunks supporting ISDN trunk features such as DCS+ and QSIG

• Generic tie-trunks permitting interconnection with H.323 v2-compliant switches from other vendors

• Direct-inward-dial (DID) public trunks providing access to the switch for unregistered users