Hybrid

It is also a good techinque.
Hybrid positioning means combination of network-based  handset-based technologies for location determination. One example would be some modes of Assisted GPS,  Both types of data are thus used by the telephone to make the location more accurate Alternatively tracking with both systems can also occur by having the phone attain his GPS-location directly from the satellites, and then having the information sent via the network to the person that is trying to locate the telephone.