Completely free tool: no ads, nu contact info selling.

After you authorize a phone number he can send an SMS with a specific content to your phone and this app will reply with LAST KNOWN location ( from GSP or WI-FI) AND the GSM location data ( MCC, MNC, Cell-id, LAC).
It will not start getting the new location of you, it will be an instant SMS reply.
The GSM location information can be transformed to a GPS location with low accuracy with 3rd party tool ( not included)

It is a free app with some effort already: Make sure you have donated / supported the development before asking bug fixes, improvements!