Abstract: A telephone apparatus (1) in a mobile telephone system providing a conditional call divert service causing an incoming call to proceed as a normal call or be redirected to a different number. The telephone apparatus has memory means (16) for storing coded telephone number entries. Each telephone number entry includes a group identification field for storing a value identifying its telephone number group, and the telephone apparatus further has control circuit means (15) enabling optional operation modes of the telephone. One mode causes an incoming call from a telephone having a subscriber number which is a member of a telephone number group associated with the mode to proceed as a normal call, and an incoming call from another telephone having a subscriber number which is not a member of the group to be redirected to a preset number.