AT&T is planning to raise its early termination fees for smartphones and netbooks from $175 to $325, Dow Jones reports, noting that the move comes amid rumors that AT&T may lose its iPhone exclusivity over the next year. Thankfully for current AT&T iPhone customers, the rate changes will not affect current contracts; instead, they will apply to all new and renewing customers beginning June 1. Notably, the higher cancellation fees will apply to any new iPhone customers who purchase the next-generation model expected to be announced at Apple’s 2010 WWDC conference in early June. While the termination fees for smartphones will rise, the same fees will actually drop by $25 for feature or messaging phone contracts. Earlier this week, AT&T Mobility CEO Ralph de la Vega made several comments relating to the possibility of AT&T customers leaving when the company’s iPhone exclusivity ends, noting that 70% of customers are on family plans, which can be a pain to move over to a new carrier, and 40% are on corporate discount plans.