Sprint isn't the only one with a new push to talk network. AT&T's Enhanced Push to Talk is still in a limited pilot program, but the company has announced that it will be doubling the number of businesses that can participate. Enhanced PTT combines standard walkie-talkie phones with a mobile data service and app integration; trials have been running since late February. Assuming all goes well, it's set for release later this year.

In preparation, AT&T has said it will be announcing five smartphones that are compatible with Enhanced PTT. That will include multiple devices from Samsung, both ruggedized phones and those in the Samsung Approved for Enterprise (SAFE) program. The new push to talk system is meant to work on a wide range of feature phones, smartphones, and specialized devices, but AT&T is pushing smartphones as a way to combine traditional phone communication with apps that replace clipboards or separate computer systems. Interested businesses can sign up using AT&T's form here.