Precise location of a Moblie phone. Conversion formula or upgrade

Hi
I'm working on a project to find out if a smartphone of any make can be modified to precisely locate its position in easting and northing coordinates, to within 10mm +-.
Would there be a soft ware upgrade required through a independent source ????
Would there be a need to upgrade the antenna ????
Introduce a additional attachment to the the mobile phone???
Is there a programme that will formulate the longitude & latitude from compass too easting&northing???
I hope some one is up for the challenge