How are events synchronization and data representation handled during a session of remote conversation, such as when you speak to someone over the phone?

Consider inter-human communications.

A session is initiated when the phone rings and is picked up at the receiving end. A “hello” from the callee typically starts the conversation, followed by the caller identifying herself/himself. The two sides then take turns to speak, using pauses or explicit words to signify a new turn.
Data representation: a common language (possibly sign language) will have to be spoken. The sound wave is converted to electric signals transmitted over the phone line, and decoded at the other end.