Sources at Apple have told the Boy Genius Report that a revised iPhone 4 model is currently in the final phases of field testing before release. This model revision is known as "iPhone3,2" and may be launched ahead of Apple's typical summer iPhone refresh cycle. Speculation is rampant over exactly what revisions are coming to the iPhone 4.
The leading contender is a CDMA-compatible version of the iPhone 4, which could be offered by either Sprint or Verizon Wireless in the US. Although this would make sense given the impending end of AT&T exclusivity, BGR also reports that the new iPhone 4 retains a SIM card slot. SIM cards are used on GSM networks like AT&T and T-Mobile.
It's possible that a long-rumored dual mode iPhone 4 could launch, meaning that one iPhone model could connect to multiple networks. Qualcomm hybrid chipsets would make it possible for one iPhone to communicate on networks using either GSM or CDMA technology. Another reason for a SIM card slot on to be installed on a CDMA iPhone would be to provide global roaming capabilities.
With any refresh of the iPhone 4, Apple is likely to redesign the antenna to prevent the signal issues experienced by users. The external antenna could be coated with something to prevent skin contact directly on the antenna, or the different parts of the antenna could be divided in a different location, preventing the "death grip" phenomenon.Apple has delayed the launch of white iPhone 4 models, and some have speculated that any antenna or other hardware changes would also be included in the white iPhone 4. Steve Jobs stated that the white iPhone would be released later this year. Apple is reportedly having problems with the white iPhone 4 manufacturing process, with paint colors on glass not meeting quality standards.
According to BGR, the iPhone 5 is currently in the engineering verification test phase at Apple, much further from public release than the revised iPhone 4.