In addition to expanding its Enhanced Push-to-Talk to the Apple iPhone, AT&T also announced that the service will now work over Wi-Fi. That is a big boost for AT&T considering that it sports the largest Wi-Fi network in the U.S. including 32,000 Hot Spots.
Adding PTT capabilities to the Apple iPhone 5 and Apple iPhone 4S allows for instant communication of time sensitive messages using a system that takes less than one second to setup. And a indicator shows you a busy/free status for your contacts. If you own the Apple iPhone 5 or Apple iPhone 4S, and AT&T is your carrier, click on the sourcelink to download the free app. It should be noted that the service requires a subscription and your John Hancock on some paperwork. Downloading the app is just the first step toward making your iPhone PTT capable.
source: AT&TEnhancedPTT via MobileBurn