The resources thus assigned are used exclusively by the customer for the duration of the call. A call record for billing purposes is created during this phase. When the customer terminates the call the resources return to an idle state to make them available for new calls. The call record is completed and stored. All circuit-switched networks operate in this way, but there are different types of circuit switches, categorized by what they connect to.
Local switches connect to end-users.
Tandem switches connect to local switches. Circuit switching results in constant, and usually low, delay, which is perfect for voice. However, it tends to be wasteful of bandwidth for data transmission because the connection is tied up for the entire duration of the call, even between data bursts when network resources are not needed. A better technology for data connections is packet switching. Unlike circuit switching, this type of connection does not dedicate resources for a particular user.