Communication without all the hassle. Is it to be presumed that cellular technology is the only form of external communication the world has to offer.
I'd say it would be speaking, for that is the only thing I got from 10 minutes of brainstorming. If the message is an universal one, like shining a light at a plane means "help me", and that there is the appropriate materials, it could be done, but I wouldn't count on that as communication since you could not make it so that you send a complete sentence, but only what it has to offer, in this case, "help me".
Then, speaking is not that bad. You can instantaneously send a message at the speed of sound, one that most can comprehend if you're speaking in the same language, easily yes because people inside your speaking distance are often in the same country as you. You can also whisper, needing a closer distance but also safe from other peoples ears.
If this is in another world, not necessarily more high tech as this one, there could be underground lines which you connect to through an id, then put earphones on, not counting as wireless, then entering a number to connect to another person on the line. If there are enough lines, and people have specific glasses that allow only them to see their share of information on the line and alerting them, it could be good enough. There would just be people who don't understand why there are no cell phones with this technology.
Phones at home would be similar, since they are in the same place, it could allow for wired only connection, but it isn't as simple as cell phones.
In all of this case, the only method that allows the communication near to the simplicity and safeness of the cell phone is the ground lines.