Also, new data sheds light on the Lumia 640's growth, and we compare upgrade-distribution rates between Windows Phone, iOS, and Android.
Who gets Windows 10 Mobile?
The March numbers reveal that 15.2 percent of all existing Windows Phone that are capable of running Windows 10 Mobile already are on the OS. Another 35.2 percent are capable of upgrading to the new mobile OS launched this month, at least, in theory assuming little carrier interference and regional delays. That brings the total number of Windows 10 Mobile devices - in theory - up to 50.4 percent of active phones.
Doing math leaves 49.6 percent of all Windows Phones in use as not being capable of running Windows 10 Mobile. Many of those phones are ones with 512MB of RAM or older Qualcomm S4 chipsets, which, according to Microsoft were cut from upgrade eligibility due to negative Insider feedback.
See the full list of eligible Windows 10 Mobile devices here.
Microsoft has said there is no 'wave 2' of device upgrades coming, however, there is some reconsideration for phones like the Verizon Lumia Icon, which has a dedicated following.
HTC is passing on upgrading the One M8 to Windows 10 Mobile due to a small install base and the costs of paying carriers to test the update (versus any return benefit). Perhaps that is of no surprise as the company is struggling financially amongst fierce competition in the Android space.
Good or bad?
Is that 50 percent number for Windows 10 Mobile upgrades good or bad? Considering that the update is not hitting all of those devices just yet and things like carriers, regional availability, OEM support, and more come into play, the number is likely lower.
Looking at current Android stats and just 2.3 percent of their install base is on Android 6.0 (Marshmallow) with 36 percent on Android 5.0/5.1 aka Lollipop (which was released in late 2014).
Around 34 percent of Android users are still on KitKat, which came out in early 2013, but mostly in 2014.
You can see what our sister site, Android Central, thinks about the Windows 10 Mobile upgrade by reading 'Microsoft can teach Android makers a thing or two about updates'.
Apple, on the other hand, has a more elegant story to tell with 79 percent of all active iPhones and iPads on iOS 9 as of this month.
Once again, Windows Phone falls in between Apple, who always sets the bar and Android, who tends to lower it. However, none of that will make your pleased if your phone is in the ineligible bunch for Windows 10 Mobile.
Windows 10 Mobile share is up again
In related news, AdDuplex also noted that Windows 10 Mobile accounts for 7.7 percent of the Windows Phone OS market and beating Windows Phone 8.0 at 7.4% and Windows Phone 7.x at 3.9 percent. That's a 2.4 percent bump for Windows 10 Mobile since the last numbers.
There is still an uphill battle, however, as Windows Phone 8.1 makes up a massive 81.1 percent of the OS version on all Windows Phones. A mix of in-situ upgrades to current hardware and new Windows 10 Mobile hardware will be needed to overthrow Windows Phone 8.1.
Lumia 640 rising and Lumia 520 going to second place?
Finally, the Lumia 640, which is Windows 10 Mobile upgradable, is still one of the fastest growing phones with a global 0.9 percent rise amongst all Windows Phone devices. The Lumia 640 now accounts for 7.3 percent globally and is slowly catching up to the Lumia 520 (12.1%), Lumia 535 (12.0%) and Lumia 630 (8.8%).
AdDuplex suggests this may be the last month with the Lumia 520 as the top Windows Phone as it lost 0.5 percent share.
Unfortunately, new OEMs are yet to gain any share from Microsoft's Lumia devices as their share has actually increased by 0.34 percent. That means 97.21 percent of all Windows Phones are still NOKIA/Microsoft. BLU is not seeing much luck with just an infinitesimal 0.01% gain while HTC, Samsung, Huawei and 'Other' are all down slightly.
The numbers from AdDuplex are collected through their in-app advertising that is prevalent in over 5,000 apps in the Windows Phone Store. That data serve as an important metric within the Windows Phone ecosystem. The full AdDuplex report for March will be posted on their blog at http://blog.adduplex.com on Thursday (March 24th)