Almost everything is exactly the same as on your desktop computer. The only thing that's different is what goes on under your TCP/IP layers. Your Phone has a m

Almost everything is exactly the same as on your desktop computer. The only thing that's different is what goes on under your TCP/IP layers. Your Phone has a modem built in, that modulates a digital signal over a carrier wave at a certain frequency (set of frequencies, depending on the channel access protocol) the modulated carrier wave is sent out to the cellphone tower. When the modem is supposed to receive, when it's allowed to send, how it negotiates these things is all strictly defined by protocols the telecom industry has standardized on. I can't say I'm an expert on these protocols, there's a whole bunch of them. They are grouped in protocol stacks with familiar names like GPRS, EDGE, UMTS, LTE. These protocols besides making optimal use of their available bandwidth taking into account all kinds of noise, disturbances, moving from tower to tower, other phones also specify how the communication should be encrypted. The encoding/decoding of these protocols is usually done by an integrated circuit in your phone that's separate from the rest of the phone's functionality, to prevent you from tampering with it (and to ensure reliability I guess). So all your phone's general operating system has to do is interface with that circuit to get neat IP packets.