▪Extension dialing. The dialer dials one number on demand for each extension. This type of dialing is also known as power dialing. See Extension dialing for more information.

▪Group dialing. Interviewers are allocated to groups (all interviewers may be members of a single group) and the dialer dials numbers for the group as a whole. Interviewers are associated with a group and calls are then made for the group instead of for the extension. The dialer makes several calls for a group in anticipation of an interviewer being available to take a call as each connection is made. When a group call is connected it is transferred to the interviewer who has been waiting the longest in that group.