In switched networks with circuit switching, call setup is based on the exchange of information about the readiness to send and receive between two communication partners. The connection can be established by automatic or manual dialing of the subscriber number. The indication takes place on the receiving side after the connection is established.
The time required to establish a connection is the connection setup time. It is the time required until both communication partners have agreed on the connection modalities and a physical connection exists between the partners. The time required to establish a connection depends on the network concept. For example, it takes several seconds to establish a connection in the conventional telephone network, less than one second in ISDN, and around 100 ms in Long Term Evolution( LTE).