Because the iPhone 5 doesn't have an extra antenna, it won't support simultaneous voice and data: http://www.macrumors.com/2012/09/13/verizon-iphone-5-will-no...

I've got a thunderbolt on Verizon and I do 3G and voice as well as 4G and voice at the same time. Some googling seems to show that it uses two antennae to do this, but to me as an end user it works great.

Yea I'm pretty sure with LTE that's possible. It's definitely not with 3G or below though.

But overall, I've never been happy with any smartphone. I pay $80/month for unlimited data, 350 minutes, unlimited texts.

After time, it always slows down, becomes buggy, bluetooth link cuts out, or the entire phone crashes. I don't know if it's designed to do this or it happens through the process of apps being updated and the phone becoming obsolete. This could probably be tested... if a phone was never updated, ever but that could probably lead to some security/privacy issues due to app bugs, os bugs, etc. Just seems like $80 is a lot to have this thing constantly bug up.

Until Verizon's network supports VoLTE, you can not talk and use data at the same time with the iPhone 5.