Saint Helena has the international calling code +290 which, since 2006, Tristan da Cunha shares. Saint Helena telephone numbers changed from 4 to <answer>5</answer> digits on 1 October 2013 by being prefixed with the digit "2", i.e. 2xxxx, with the range <answer>5</answer>xxxx being reserved for mobile numbering, and 8xxx being used for Tristan da Cunha numbers (these still shown as 4 digits).
How many digits did Saint Helena change their phone numbers to?
5