Apple on Thursday began inviting many of its iPhone developers to begin live testing of applications that will make use of the company's upcoming Push Notifications service.

"Start testing your applications using the Apple Push Notification service today," the company said in an email blast to registered iPhone developers. "Log in to the iPhone Dev Center and review the Apple Push Notification Programming Guide and Getting Started video."

Apple explained that Team Agents can log in to the iPhone Developer Program Portal and proceed to the App ID section to perform the necessary steps needed for developers to enable and test applications using the new service.

Under development for nearly a year now, the push notifications service is Apple's alternative to allowing true background processes — which chew up system resources and rapidly drain battery life — on its iPhone and iPod touch handhelds.

Instead, the iPhone maker's approach calls for applications that can quit but continue to "listen" for data on a universal network channel capable of sending messages and other notifications. This frees up system resources while still permitting applications, such as instant message clients, to keep an ear out for incoming transmissions.

While previewing iPhone Software 3.0 last month, which will be the first version of the software to support the push service, iPhone software chief Scott Forstall said devices running rival mobile operating systems from RIM and Microsoft see standby time fall by 80 percent or more with background processes enabled.

In contrast, Apple's tests show its push notification system inflicts only a 23 percent hit on standby time when enabled. It will allow developers to push a handful of different notifications to users who request the updates, namely icon badges, text messages, and alert sounds.

Until today, live testing of the push notification service was believed to be restricted to an extremely small subset of developers. While seeding iPhone Software 3.0 beta 2 last week, Apple told developers that they could begin writing applications that make use of the service, but warned that access to test those applications live would be limited at first, gradually expanding to more developers over time.