When asked why Google Maps was dropped from Apple's iOS 6 mobile operating system, both Apple and Google regularly refer to the end of the original five-year partnership the two companies signed in 2007 when the first iPhones debuted.

Skeptics, however, have always felt there was certainly more to the change, including the increasing competitive friction between Apple and Google as they battle more directly in the mobile marketplace.

Exactly, says a new report from The Wall Street Journal's All Things Digital site, which describes the chasm as rooted in the lack of voice-guided navigation in Google Maps. "… multiple sources familiar with Apple’s thinking say the company felt it had no choice but to replace Google Maps with its own, because of a disagreement over a key feature: Voice-guided turn-by-turn driving directions," reported ATD.

While Google's own Android nav app has had voice navigation features for a while, it's inclusion in iOS was apparently not part of the original Apple-Google deal. That feature is what Apple wanted in a new deal, the story reported. "Requiring iPhone users to look directly at handsets for directions and manually move through each step—while Android users enjoyed native voice-guided instructions—put Apple at a clear disadvantage in the mobile space."

For Apple, it was ultimately something that couldn't be left out of any continued map offerings from Google. On the flip side, since Google's Android already has a leg up on Apple with the voice nav services, the idea of offering the same capabilities to Apple wasn't seen as wise, the report continued.

“There were a number of issues inflaming negotiations, but voice navigation was the biggest,” a source told ATD. “Ultimately, it was a deal-breaker.”

Apple's removal of Google Maps, which had been built in to iOS since the debut of the iPhone in 2007, in favor of Apple's own Maps application was announced in May.

After Apple's new iOS 6 operating system became available for download Sept. 19, many users around the world began taking to the Internet to loudly vent their frustrations about the loss of Google Maps in the company's new mobile operating system for the iPhone, iPad and iPod Touch. The new Apple Maps app has been panned, based on dozens of posts on Twitter and other social media sites.

Among the loudest complaints are incorrect maps, a lack of points of interest being displayed and a total lack of transit directions for mass transit systems in large cities, which Apple says it will be adding later.

The controversy has gotten even more heated as Google looks at building and offering a stand-alone Google Maps app that would work with iOS 6 and would be made available through Apple's App Store.

Google Chairman Eric Schmidt talked about just such an option on Sept. 24 and said that Apple's iOS 6 would have been better if it had retained the built-in Google Maps services.

"We haven't done anything yet with Google Maps," Schmidt said in a meeting with reporters in Tokyo, according to a Bloomberg report. "Apple would 'have to approve it. It's their choice,'" he said, declining to comment on whether Google has yet even submitted an application to Apple to distribute a Google maps for iOS 6 app in the App Store.

In a story in The Wall Street Journal, Schmidt said the talks are continuing between Apple and Google over the fate of the Google Maps app in the App Store and other issues. "We've not done anything yet," said Schmidt, according to The Journal. "We've been in touch with them for a long time [about Google Maps], and we talk to them every day."

Schmidt "declined to explain the nature of talks between Apple and Google, describing Apple as a 'huge Internet search partner,'" The Journal reported. "In my opinion it would have been better to retain our maps," he said. "It's their decision. I'll let them describe it."

The Apple-Google brouhaha over Google Maps isn't the only place where the two have been parting ways this year. Apple also announced in August that it was removing the YouTube player from iOS 6, which like Google Maps had been part of the operating system since the launch of the iPhone in 2007.