AT&T iPhone service and Wi-Fi?

We get really bad phone service where I live so you can't talk to people over the phone. So I was wondering if connecting to Wi-Fi would help in any way because we have really fast Internet. So since our signal is bad will Wi-Fi give you better signal to talk to people

Http://www.att.com/standalone/3gmicrocell/?fbid=De8cMdMWY3S

You can get a wi-fi boost for your cell coverage!

Or change service providers to http://BestPhoneService.biz