user: Question: How many mobile phones were there as of April 2013?
Columns: ['Country or region', 'Number of mobile phones', 'Population', '# of phones as % of population', 'Last updated date']
Types: ['text', 'text', 'text', 'real', 'text']
Sample row: ['World', 'Over 6.8 billion', '7,012,000,000', 87.0, '2013']
SQL:

assistant: SELECT SUM("Number of mobile phones") FROM "Table" WHERE "Last updated date" = 'April 2013';