In the world there are a bunch of computers and software interconnected by wires (some copper, some glass with a bit of translation from photons to electrons and back) so the computers can talk to each other. And at various fewer points on the globe, those internet, wire-transferred signals get broadcast locally (in coffee shops and in big houses or business buildings, relayed into the cabins of airplanes in flight, or what have you) so that computers that are equipped to receive the locally broadcast signals and broadcast back to them (like laptops and tablets) can access the world wide network of wires and computers via radio wave (well, whatever the bandwidth) signals. The signals traveling in the air as radio (or whatever) waves get translated into electron signals for computers.
Then there's landline and cell phone telephones. Once upon a time all the telephones talked to each other along a world wide web of wires (mostly) using switch stations in between. Now those same wires can be used to transfer internet signals for computers, but note here also that along came a world wide (-ish) network of cell phone towers. Those towers are connected to the telephone wires of course, but in any case each tower broadcasts and receives radio wave (or whatever bandwidth) signals within a certain radius (beyond which the signal becomes too weak, like the radio in your car after a certain distance, depending on broadcast strength/energy). In high population density areas, there are a lot of these towers with overlapping broadcast radii (radius-es) are sophisticated ways of transferring one's phone call from one tower to the next as one drives so that the calls are not (hopefully) interrupted.
Nowadays and increasingly, cell phone towers are used to broadcast and receive signals to and from smart phones that are set up to connect to the computer-based internet. Yup. Via cell phone towers, smart cell phones connect to the world wide web--for email, Facebook, Youtube, or whatever. Same with tablets (iPad, etc.) of various sizes. Could some of the latter be pocket PCs? Or smart phones?
Then there's the set of 24 or so GPS satellites that the US Airforce sent into orbit in various trajectories thanks to US taxpayers and US military interests. The whole world then uses these satellites for landing aircraft or tracking the migration of animals with tracking devices attached or for finding where to drive when they have GPS devices
installed. And no, the weak GPS signals, so far as I know, are not relayed via the internet or cell phone towers. They are separate. So I assume the smart phone-cell phones that use the GPS signals do so in the same way that GPS devices do.
Cell phones with GPS capability are pocket sized. So are many GPS devices. Some have screens for travelers, some do not or have only modest screens, such as for cyclists or runners rather than for those looking for the right lane to be in to enter the highway.
Hope this helps.