A trunk, also known as a Session Initiation Protocol (SIP) trunk, is a high capacity communications line that delivers voice calls and data from a client location to the internet. Trunks have been around for decades and are used worldwide. Trunks often connect switching stations with other switching stations or PBXs to switching stations in a point-to-point, dedicated connection.
SIP trunks have 24 channels, each of which can transmit voice or digital data at a rate of 64 Kbps, for a combined rate of 1.544 Mbps. Depending on the configuration, the 24 channels can each support a phone call at the same time. The T1 trunk can also be configured so that some of the channels support voice and some support data, or all 24 channels can be dedicated to data. Compare this to a single, traditional analog line that can only handle one call at time and it's easy to see why T1 trunks are a better solution for businesses.
Use of trunks is on the decline due to the introduction of faster, cheaper connectivity options. However, they remain one of the most reliable forms of connectivity.
