Editing Routing in the PSTN (section)

{{short description|Process used to route telephone calls across the public switched telephone network}}
{{More citations needed|date=June 2016}}

'''Routing in the PSTN''' is the process of forwarding [[Telephone|telephone calls]] between the constituent telephone networks that comprise the [[public switched telephone network]] (PSTN).

Telephone calls are routed across a network of potentially many switching systems, often owned by different [[telephone carrier]]s.  Switching systems are connected with [[Trunking|trunks]].  Each switch may have many neighbors.   Neighboring switches  owned by different operators are connected at interconnect points.

The PSTN is a network that uses [[destination routing]] to direct calls from origin to the recipient. It is not a full [[mesh network]] with the [[Node (networking)|nodes]] of every operator directly connected to those of every other, which would be impractical and inefficient. Therefore, calls may be routed through intermediate operator networks before they reach their final destination.  Efficient [[least-cost routing]] is an important procedure in PSTN routing.