Why does the service icon change on a cell phone depending on which tower youre connected to?

Sometimes it%26#39;s a service bar, other times it%26#39;s a capital E, and I have even seen it with a %26#39;3G%26#39; icon. What do these mean?

Answers:

E means you have good service.

3G means that you have good internet service, which means if you are watching a video on the internet it will not take as long for it to load, and the speed will be better.

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