It's all hands on deck at Microsoft right now: with a variety of high-visibility phone launches from partners scheduled before the end of the year, the company has not yet finished the Windows Phone 8 software, The Verge has learned.

Microsoft and Nokia's Lumia 920 announcement last week may have been a preemptive strike against Apple's iPhone 5, but both companies are now working overtime to ensure Windows Phone 8 launches on schedule. We're told by multiple sources that Microsoft had originally planned to launch Windows Phone 8 in early October, ahead of the launch of Windows 8. Microsoft is now targeting an October 29th software launch event with devices available throughout November, a slight delay to its original schedule.

Delays and bugs during testing have pushed back the launch, and associated devices, by weeks. We're told that HTC in particular has had a tough time testing one of its Windows Phone 8 devices, a process that has impacted its ability to announce handsets as early as Samsung and Nokia. Microsoft has been working closely with US carriers to ensure testing times are reduced. In some cases carriers may ship devices without any of the usual customizations, to reduce test times and ensure a November launch schedule remains likely. The tight schedule means that any delays in final carrier testing will impact the availability dates of Windows Phone 8 devices.

Nokia launched its latest Lumia devices last week, but members of the press were prevented from playing with the Windows Phone 8 operating system. We're told that this was mainly due to Microsoft's fears over unannounced features and the fact that some parts of the OS were unstable. Network operator EE announced its first 4G service for the UK today, backed with an exclusivity deal on the Lumia 920. Although devices were on display at the event, Nokia had to cover them in glass to prevent onlookers from playing with Windows Phone 8. The company has also been sending out dummy devices to members of the press in the UK.

Microsoft is tentatively aiming for a late October launch of Windows Phone 8, when we expect the company to reveal all of the remaining features like Kid's Corner and a new Rooms option. A Software Development Kit (SDK) preview is due on September 12th, and testing is underway at AT&T and Verizon for Samsung, HTC, and Nokia devices. If the testing goes smoothly then we expect to see Nokia's devices debut on November 2nd, with other handsets to be made available throughout November. It's not quite the October launch that Microsoft was aiming for, but the momentum of Windows 8 and a big advertising campaign planned for Surface will make up for the slip — as long as all parties involved can stick to the new schedule.