Using a mobile phone to make a call from data exchange mode

For ordinary wired phones, when two parties talk, most of them are analog signal transmission. However, dialing includes dual-tone multi-frequency dialing and pulse dialing, as well as data transmission when the mobile phone with caller ID function rings. Now some solidification can send short messages, which is also data transmission.

Telephone communication can be divided into three stages: call establishment, communication and call cancellation, and the process of telephone communication is the process of circuit switching. Therefore, the basic process of corresponding circuit switching can be divided into three stages: connection establishment, information transmission and connection release.