How the mobile phones sending and receiving signals from the satellites? who is providing these services at free of cost?
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@jam yes, except he's apparently not interested in how it works but rather how it's funded (which is of course related). – jwenting Jun 24 '14 at 12:45
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@jwenting the top answer on that question does cover the issue of funding :) – jam Jun 24 '14 at 13:11
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@jam it's also wrong in stating the GPS in phones only works when you have cell network... It works fine even without a sim card. – jwenting Jun 24 '14 at 13:12
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http://en.wikipedia.org/wiki/GPS Please try a little research before asking questions. – Mike Gardner Jun 24 '14 at 13:30
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You clearly don't know how GPS works. You don't send anything to the satellites, you only receive.
The satellites are operated by the US armed forces, a public service as a side effect of their military use. You don't have to pay anything for that (except for US taxpayers as part of the defense budget, but there's no extra cost for the civilian use).
The satellites each send a very accurate time signal at very regular intervals. A GPS receiver listens to those signals, and based on them can calculate where it is itself to within a few meters (though that accuracy can be reduced if needed by the operators of the satellites, say in times of war).
That's all there is to it.
Of course cellphones also use position data from cellphone towers to calculate their location through triangulation. The position of each tower is known, the phone queries all towers it can talk to, and again can then calculate where it is.
It can even do so based on the location of known WiFi networks.
jwenting
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