In addition, the transport layer allows IMS devices to make and receive calls to and from the PSTN network or other circuit-switched networks via the PSTN gateway.
In a circuit-switchednetwork when you use a circuit, you have the full circuit for the time that you are using the circuit without competition from other users.
在电路交换网络中使用电路时，您在使用该电路的时间内将拥有整个电路，不会与其他用户争用。
3
Dynamic routing technology of circuit-switchednetwork is critical to bring non-hierarchical network into full services and improve the grade of service eventually.