accepts the request to start a conversation. A party is most commonly a single person, but can be a group of people (i.e. conference call) or a machine (i.e. fax). In some contexts, the term A-Number refers to the caller and B-Number refers to the called party.

The telephone call was enabled by multiple inventions in the mid- to late-19th century including the telephone. Initial technology involved point-to-point electrical wire connections