Trunk

In a communications network, a trunk is a transmission channel between two points that acts as either switching centers or as nodes. Trunks enable network access to multiple clients simultaneously by sharing the lines or ports instead of proving them on an individual basis. A trunk can be a physical circuit between a switchboard and related telecommunications equipment, or can be used to interconnect the switches that form networks. In PBX systems, trunk lines are the lines that connect the PBX to the PSTN. Trunking can help businesses cut cost by saving them money on purchasing multiple individual phone lines that more often than not won’t be in use simultaneously. Data formats able to transmit trunk line communications are T1, E1, ISDN, or PRI.