Twelve years for the first billion users, two and a half years for the second billion. Those are the staggering statistics being flaunted by the GSM Association this week as they prepare to sign up their two billionth customer, driving home the exponential growth mobile carriers worldwide have enjoyed as of late. Although China represents by far the largest single user base with over 370 million, Latin America and the Caribbean brought their "A" game last year, holding the titles for largest subscriber growth rate (97%) thanks to numerous carriers selecting GSM as their CDMA / TDMA upgrade path. So, how many peeps worldwide are toting cellphones, regardless of technology? According to the GSMA, there are 2.29 billion, making GSM the overwhelming standard of choice; we're guessing you can figure out who slots in at number two.