More than 2.5 trillion SMS text messages have been sent from cell phones worldwide this year. This means that text messaging brings in billions of dollars in revenue for the world’s four major cell phone carriers. In fact, it’s estimated that SMS text messaging revenues could even top $165 billion by 2011. (SMS stands for “Short Message Service”.) So, if the text messaging business is so lucrative, why have AT&T, Sprint, T-Mobile, and Verizon Wireless doubled the pay-per-use-price for messages from 10 cents to 20 cents?