Portugal changed to a closed telephone numbering plan on 31 October 1999; previously, the trunk prefix was '0', but this was dropped. For landline subscribers, the area code, prefixed by the digit '2', was incorporated into the subscriber's number. For mobile subscribers, formerly seven (to call another subscriber using the same operator) or eleven (to call any mobile subscriber) digits were used. For special number ranges, formerly ten digits were used, but the initial '0' was dropped. These changes made that nine digits were used for all calls after 1999.