So as an example a UK landline may best be searched, as phrase and changing the spacing, firstly as
''01823123456'' & ''01823 123456'' & ''01823 123 456'' and then as
''1823123456'' & ''1823 123456'' & ''1823 123 456'' and then as
''441823123456'' & ''441823 123456'' & ''441823 123 456''
And an American one may best be searched, as phrase and changing the spacing, firstly as
''09171234567'' & ''0917 123 4567'' and then as
''9171234567'' & ''917 123 4567'' and then as
''19171234567'' & ''1917 123 4567''