When minimum number of complex characters is set to 1, it is not enforced on some Windows Phones
Posted by Donna Magada on 18 November 2011 11:59 AM

When the minimum number of complex characters is set to 1, users are still able to create a password on the device with no complex characters.  This does not occur when the minimum number of complex characters is set to a value greater than 1.  B6460 and B2606

This has been observed on:

-LG Quantum running Windows Phone 7.5
-Nokia Lumia 920 running Windows Phone 8