Definīcija: The process used to authenticate users calling in to a network. During callback, the network validates the caller's username and password, hangs up, and then returns the call, usually to a preauthorized number. This process prevents unauthorized access to an account even if an individual's logon ID and password have been stolen.
Definīcija: Telefonu sistēmas funkcija, kas gadījumā, ja izsaucamais telefons ir aizņemts, nodrošina iespēju pēc telefona atbrīvošanas izsaucēju savienot ar vēlamo telefona numuru.