Less than a week after they released software that unlocked Windows Phone 7 (WP7) smartphones to let users install unauthorised applications, three developers have yanked the tool from distribution.

The trio, Rafael Rivera, Chris Walsh and Long Zheng, said Wednesday that they pulled ChevronWP7 after reaching agreement with Microsoft, which has pledged to talk with them about officially supporting applications not available through the company's approved software marketplace.

Rivera, Walsh and Zheng released ChevronWP7 last week , saying the unlocking tool allowed "sideloading" of unapproved or experimental applications "that otherwise can't be published to the [Microsoft] Marketplace, such as those which access private or native APIs."

Mutual understanding

Today, the three developers announced ChevronWP7's demise on their blog, saying the decision was prompted by a discussion with Brandon Watson, the director of developer experience for Microsoft's Windows Phone 7 operating system.

"Through this discussion, we established a mutual understanding of our intent to enable homebrew opportunities and to open the Windows Phone 7 platform for broader access to developers and users," wrote Rivera, Walsh and Zheng.

"To pursue these goals with Microsoft's support, Brandon Watson has agreed to engage in father discussions with us about officially facilitating homebrew development on WP7. To fast track discussions, we are discontinuing the unlocking tool effective immediately."

Watson's call came just a day after Rivera, Walsh and Zheng published their first application, a custom ringtone manager. Installing the program required a tool within the WP7 SDK (software developers kit).

Both parties declined today to provide additional detail about their talks and Microsoft's promise. A Microsoft spokeswoman did confirm that the company had spoken with the ChevronWP7 developers and that the trio's account was accurate.

"Our talks are just beginning, so there's nothing else to share [at the moment]," said Rivera.

Microsoft issues warning

Last week, Microsoft discouraged WP7 users from trying ChevronWP7, saying that, "Attempting to unlock a device could void the warranty, disable phone functionality, interrupt access to Windows Phone 7 services or render the phone permanently unusable."

Like Apple, Microsoft vets mobile apps before loading them into its Marketplace store. Microsoft argued that the approval process insured that only high quality, non-malicious software made it onto the smartphones powered by its mobile operating system.

Google takes a completely different tack, letting Android users install any app from any source.

Rivera said that approximately 27,000 copies of ChevronWP7 had been downloaded in the six days it was available.

Users who have already installed ChevronWP7 can uninstall it with the usual "click-hold-uninstall" maneuver on a WP7 device, Rivera added. "No debris is left behind," he said.

The three developers are also working on a way for users to install the ringtone manager.