It's been about a month and a half since AT&T Inc. (NYSE: T) lost exclusivity of Apple Inc. (Nasdaq: AAPL)'s iPhone and Verizon Wireless began offering a CDMA version, and so far things have been going "pretty well as expected," says Pete Ritcher, SVP of mobility finance at AT&T. (See Verizon Finally Gets the iPhone 4 .)

Responding to questions at a Credit Suisse conference Wednesday, Ritcher said that the biggest customer losses from subs jumping ship for the Verizon iPhone would occur in the first quarters of the year, so the worst should be over soon.

AT&T also took a number of steps to ensure it was prepared to lose exclusivity, Ritcher said, including adding 12 Android devices to the mix and bumping up its marketing efforts around AT&T's advantages -- simultaneous voice and data and speed. It also had upwards of 90 percent of its customer base on contract, including a number of family or business plans, which kept those customers with AT&T. (See AT&T Beats Verizon on iPhone Speed, AT&T's Answer to the Verizon iPhone: Android & Friends and Verizon Rivals Play iPhone Defense.)

"All those things together will mitigate what some thought would be a large deflection of our customer base," Ritcher said. (See Verizon Sells Out iPhone Pre-Orders, Throttles 3G.)

In addition, AT&T tweaked its rate plans to be more competitive on pricing and adjust for the fact that voice revenues are declining as data becomes a larger portion of its revenue stream, he added. AT&T also reduced the price of its iPhone 3GS to just $50 ahead of Verizon's launch. (See Tablet Prep: AT&T & Verizon Shake Up Pricing.)

— Sarah Reedy, Senior Reporter, Light Reading Mobile