This subject has come up on more that one occasion. Most recently in OhioBarbarian’s latest diary. At this very moment there are a plethora of communications protocols available. A small list of which is here. [PDF]
These are just the current supported ones for commercial use. There are a number of other communications protocols and modes that are particular to certain applications. Like PSK31, PSK63, Olivia and on and on for HF Radio communications. Plus various WIFI and BLUETOOTH protocols.
The common thread here is that most of these protocols are hardware independent. They can be implemented of any chip set. WIFI communications itself uses a particular frequency range but this too can be changed if need be. Usually just by changing the firmware.
Nearly all computers use what is known as ASCII for text but there is also BCD, EBCDIC, BCDIC, BAUDOT, and others. There is no law that says you need to use any of these codes or protocols. One can invent their own and use it. Even for voice or audio.
Cell phones and WIFI cards and routers can be changed and reprogrammed to use any code, protocol and/or frequency range one desires. [Within certain limits of course] They use frequency hopping. That is they jump around very, very fast from one frequency to another and this jumping can be anything one wishes.
The only rule is that the receiver knows or has the appropriate application to receive the message. Thats all. There are already people experimenting with different communications protocols with over the counter equipment.
The only reason we are using TCP/IP over the Internet is because already exists and is convenient. If needed anything we chose to use/or invent will work. One of the big pluses of our current technology.