cell phones are indeed radios.-Cell phones are radio communication.-Are you kidding?The roaming charges in outer space are horrible!......
There are no cell sites in space, so they cannot use cell phones. They might be able to use the satellite phones like Iridium and similar systems, but they don't as they have adequate radio communications.
Interesting -- some of the space shuttle missions, as well as the International Space Station have Amateur Radio systems as well as their space agency links. They use these (ham radio) systems to communicate with amateur radio operators, school classes, and so on. You can look for "ARISS" at Google/Yahoo to learn more about this.
Cell phones ARE radios. But they are special radios designed so that many of them can transmit at the same time in a small area and not interfere with each other. They do this by transmitting a weak signal that cannot go outside the local cell, as the area around the nearest cell phone tower is called. Everyplace in space is WAY too far from the nearest cell for the weak signal to be received.
In space, there are no cell towers.
Plus, as already stated, cell phones are indeed radios.
Cell phones are radio communication.
