Worked for me...

Two days ahead I set up taxi to CDG for 4am. I could track drivers progress on iPhone...he arrived at 3:55 and was very pleasant and helpful. Will definitely use service again. I did call a day ahead to be sure reservation was in place. Compared to phone call, this app was much less ambiguous in selecting pick up point. For me, there were several similar addresses in Paris. Using the mapping function allowed certainty as to the correct one. The phone operater asked me my address, but seemed unsure which one to choose from her database until she checked my reservation selection from this App.

DogWalker2 about G7 TAXI – Commande de taxi