Call initiation on a device with potential for a large number of stored telephone numbers is simplified through the use of an integrated field for entry of an ambiguous filter string. As it is not clear, a priori, whether the user is manually specifying, in the integrated field, a telephone number or providing a filter string for filtering contacts, filtering is performed based on at least one filter string. Among the contacts that are part of a filtering result list, a default contact is selected for quick access.