Claiming “the largest Push-to-Talk (PTT) coverage area in American,” cellular wireless provider Cingular has announced new features for its next generation service including the ability to convert PTT calls into standard wireless voice calls.

Using a single phone number for both cellular and “walkie-talkie” calls, the enhanced PTT service also features call waiting, contact alerts that let customers know when a contact becomes available, call-me alerts for urgent PTT calls, quick group calling, and voice messaging.

Initially, Cingular is offering two handsets with PTT capability, the Samsung d357 and LG F7200. National PTT coverage for businesses is a $9.99/mo. option for cellular subscribers, and international PTT coverage is expected later this year, according to the company.