A method and apparatus for alerting a plurality of groups of telephone stations in sequence in response to receipt of a pilot directory number in a first telephone switching system first switch alerting a group of telephones; if none of the first group of telephones answers establishing a connection via a second pilot directory number to a second switch for accessing a second group of telephones and alerting the members of the second group. Advantageously, this arrangement allows a telephone call to be completed to a first preferred group of telephones before attempting to complete the call to a second group of telephones.