the iPhone 5 would need a third antenna to take advantage of Verizon's network. It doesn't have 3, so no simultaneous voice and data. other phones, like the Samsung Galaxy S III, do allow voice and data at the same time on Verizon. Here's a second article that explains the situation
http://www.pcmag.com/article2/0,2817,2409716,00.asp
http://www.pcmag.com/article2/0,2817,2409716,00.asp