How to jailbreak 3Gs running 6.0 and block certain incoming calls?

skeeter

Hello, I'm trying to block certain calls that come into my elderly father's iPhone. I bought him an older 3Gs, as it was inexpensive, and easier for him to use than an android phone. Problem is he is now getting scam calls, and I need to block these callers.

I understand there are ways to block incoming calls on iOS 6 using applications that run on a jailbroken phone. What apps do you recommend, and how do I jailbreak this older phone?

Thanks very much...

Skeeter