 This was intended as a long-term solution, but within two years 314 was almost out of numbers again due to the proliferation of cell phones, pagers and fax machines.The supply of numbers was further limited because the St. Louis LATA spills into much of southern Illinois, meaning several numbers that were part of area code 618 across the border in Illinois weren't available.As a result, most of St. Louis' outer-ring suburbs were switched to area code 636 on May 22, 1999.