Trunks

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Trunks

Trunks or PBX Trunks, as they are referred to as, are a common group of central office lines that terminate in Private Branch Exchange (PBX) systems, automatic call centers (ACD), or any system in which the customer's premises equipment selects and seizes a vacant line for incoming and outgoing calls.

Trunk lines are typically pooled facilities in the customer's PBX system. This arrangement enables station users to dial an access code, usually 9, to connect to a Trunk, which allows an outgoing call to be made. Conversely, incoming Trunk calls to a PBX terminate in the PBX common equipment and are presented to an attendant position. Trunk lines do not terminate directly on a SERT (as some Key Systems allow), rather they are brought into an RJ21X and wired from the distribution frame into the customer's PBX equipment.

The term PBX Trunk is something of a misnomer. Typically PBX trunks are tarriffed as a "line-side" service. This means that the Trunk originates in the central office on a line circuit card. Custom calling features that can be applied to other lines, such as 1FBs or Centrex lines, can usually be applied to a PBX Trunk. Other types of Trunks such as Tie lines, DID Trunks, and FX lines are provisioned on a Trunk circuit card in the central office and are often referred to as "Trunk-Side services". You may have heard the reference "line side of the switch" or "trunk side of the switch" which is indicative of the type of circuit card used. Contact a CRM Representative for more information on Trunk lines.

For more information, please fill out our Consultation Request form or contact us at Toll Free 1-888-422-0276.

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