iPhone 5 can't do voice plus data on 4G LTE

Apple's latest iPhone has the same limitation found in last year's models, keeping users on CDMA networks from using cellular data when on voice calls.
The models for both Verizon and Sprint won't let you do other tasks while making a phone call on 4G LTE networks. When you're making a voice call on either of the two networks, you'll need to be on Wi-Fi if you want to pull data inside apps, including the Safari Web browser.
"The iPhone 5 was designed to allow customers to place a voice call on the Verizon Wireless network, while simultaneously allowing customers access to the Internet over the Wi-Fi," Verizon said
"The simultaneous voice and data capability on LTE does not apply to the iPhone," Sprint said.
"AT&T customers have the ability to talk and surf simultaneously on the iPhone 5."