Unique Carrier Features You May Not Know About
Each provider does have services that it uses to distinguish itself from the others.
For some time, Sprint had the iDEN network that allowed for its "push-to-talk" feature that turned phones into walkie-talkies. Late last year, though, the company announced it would begin to phase out the network in favor of 4G and CDMA 3G starting in 2013 and completed by 2017.
Sprint has a feature/device called Airave, which increases cell reception over an area of 5,000 square feet and can handle up to 3 calls at once. It uses the customer's existing broadband connection to transmit the calls via VoIP.
T-Mobile was really ahead of the curve with Wi-Fi in the home for calling. Many of its phones will use Wi-Fi in the home if a cellular service is not available. It also offers a landline replacement service called T-Mobile @Home, built on the UMA technology for the hotspot service. It turns your home phone line into a VoIP service similar to Vonage.
AT&T is famous for being the only provider with rollover minutes, and up until recently, was the only one to offer the iPhone.
Verizon has had a number of services, most of which were most useful in the pre-smartphone era. Verizon Media Center, formerly Get It Now, was a precursor to the App Store, using Qualcomm's BREW technology (based on Java), which allowed a user to download apps, ringtones, music, games, applications, and use instant messaging on a phone. There's also VZ Navigator, a GPS app in the phones and V CAST, a high-speed audio and video on-demand service.
Winner: Tie, across all 4 carriers