Microsoft fixes Alcatel IDOL 4 Pro fingerprint sensor Hello issues

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Surprising everyone, this month's 'February update for branch 1709' from Microsoft includes new Windows Hello code that completely fixes the fingerprint recognition issues that the Alcatel IDOL 4 Pro has had since launch. 

It has been said that Microsoft's continued monthly updates to Windows 10 Mobile are small and merely fixing security vulnerabilities, but (whether thanks to common code with Windows 10 Desktop or not) there are genuine improvements still being made. Once such was in the underlying code for Windows Hello, used to access - in the IDOL 4 Pro's case* - the rear-mounted fingerprint sensor.

* This probably applies to the IDOL 4S in the USA, but I've got no way of verifying this. Can readers in the States comment?

The issue since launch (so over six months ago) has been that the Alcatel's fingerprint sensor has been incredibly fiddly to use. Anyone who's used the phone will be familiar with the following experience:

  1. You pick up the phone and put your index finger on the sensor (on the back of the IDOL 4 Pro)
  2. The whole phone vibrates, indicating that your finger is somehow misaligned (it probably is, but only by a millimetre or two)
  3. You try again, trying to centre your finger better. The phone buzzes again. Nope, the authentication is still not happy.
  4. You try for a third time. Buzzing. You're done.
  5. Having failed three times, the phone now forces you to enter your PIN number to authenticate.

This happened at least once a day to me and it was very frustrating. You do learn how to centre your finger exactly (a good case helps a lot with this) and thus avoid the 'three strikes' situation, but it required more care than I enjoyed giving to an operation which was supposed to be simple and easy.

Camera and sensor

Now, my assumption had always been that the issue was in firmware, i.e. the microcode that drove the fingerprint sensor's electronics, and that the ultra-fussy recognition has therefore a) been Alcatel's fault, and b) was unlikely therefore ever to get fixed. However, it turns out that it was Windows 10's 'Hello' authentication modules that was to blame, since this week's regular monthly patch update from Microsoft has completely fixed the issue.

Microsoft continues to fiddle (and even rewrite) its 'Hello' code, of course, not least for better fingerprint and face recognition on desktop, laptop, and so on, so maybe this shouldn't surprise me as much as it has done, but the upshot is that fingerprint sensing on the Alcatel IDOL 4 Pro has been utterly transformed after the update. My fingerprint is now detected and authenticated successfully every time, even when only part of it is on the sensor. It's something of a revelation, as you'll be gathering.

Don't get too excited, mind you - the speed of Windows Hello under Windows 10 Mobile is still lethargic. Although recognition is now perfect - any finger angle, any coverage - it still takes a good two seconds from a finger touching the sensor to the phone display powering up, the 'Hello Steve' (or whatever) message popping up, and the user interface appearing. And in a world where the Android competition has recognition and screen-on times down to a tiny fraction of a second, two seconds seems like an eternity!

Still, a major improvement is still welcome, especially at this stage in Windows 10 Mobile's life cycle. What I suspect has happened is that Microsoft has been rewriting the Hello code to improve recognition accuracy on the new Surface and partner devices and that the IDOL 4 Pro has merely benefitted from this work. I doubt Microsoft was thinking of poor W10M phone owners...


Taken together with the breaking of PDF-reading functions in Edge, this is all evidence that there's still quite a lot going on under the hood in these monthly updates to Windows 10 Mobile. Admittedly the Edge thing is negative and not positive (as with Hello), but both changes show that there's still serious work being done and that the updates aren't anywhere near as trivial as some are making out.

PS. Comments welcome if your IDOL 4S or IDOL 4 Pro is still on the Windows 10 Anniversary Update - did the fix make it to you on the 1607 branch? Also, why the flipping heck haven't you taken my advice and moved your phone onto FCU yet?(!)

PPS. Another interesting question is whether the new Hello authentication code has improved iris recognition in the Lumia 950 and 950 XL. Anecdotally, I think it has - but I'd welcome data points, since might also just be wishful thinking and my imagination!