Nearly four months after AT&T agreed to allow VoIP applications for Apple's iPhone to run over its 3G network, Apple has provided developers the necessary tools to implement the service. According to the privately held company iCall, Apple's newly updated iPhone SDK--an effort that coincided with the unveiling of the company's iPad tablet--removes restrictions that prevented VoIP over 3G. (AT&T reversed the ban following an FCC inquiry into the matter). It's unclear why it took Apple almost four months to implement the change. An Apple spokeswoman confirmed the changes. Release