I don't know what version of Android the Epic 4G runs, but on 2.2 you can have alphanumeric passwords as well as the pattern.
Settings > Security > Setup Screen Lock. Here you can set None, Pattern, PIN (numbers only), or Password (alphanumeric).
The difference between stupidity and genius is that genius has its limits.
When you take things for granted, the things you are granted, get taken.
Even a mosquito doesn't get a pat on the back until it starts to work.
Too many people miss the silver lining because they're expecting gold.
[BES 5.0.3 / GroupWise 2012 HP2]