Digital Trends – According to a survey conducted by Consumer Intelligence Research Partners, the research firm found that 30 percent of iPhone 4S owners upgraded from the iPhone 4. Since the iPhone 4 was released during June 2010, anyone upgrading to the iPhone 4S approximately 16 months later would be subject to the early termination fee issued by wireless service providers like Verizon and AT&T. For instance, the early termination fee on smartphones for AT&T is set at $325 per line minus $10 for each month of service. Anyone upgrading to the iPhone 4S that previously purchased an iPhone 4 at launch would have paid around $175 to get their hands on the new model. Verizon customers likely paid around $270 to upgrade since the CDMA version of the iPhone 4 was released during February 2011.