Besides supporting picture and text messaging, Palringo was confirmed to "soon" support vocal instant messaging over the iPhone's data connection. The free messaging app, currently available on the iTunes App Store, integrates with several existing popular instant-messaging (IM) services, and has now added vocal instant messaging functionality, also known as push-to-talk.

Supported IM services by Palringo include AOL's AIM, Google Talk, Yahoo! Messenger, Gadu Gadu, ICQ, Jabber and Windows Live Messenger. iChat, Apple's very own IM client, is also supported. The concept of push-to-talk varies in popularity around the world, according to Palringo. Both Verizon and Sprint are promoting their push-to-talk services as alternatives to each other, in the United States, Palringo reveals in a report. However, using these services, customers are tied to a specific device, a specific network, or both.

Kerry Ritz, CEO of Palringo, said, "We've completed the suite of ways in which people can communicate with each other using an iPhone, adding voice, text-based and picture instant messaging to the standard phone call, SMS and e-mail functionality of the phone. This functionality really adds value to the already-terrific iPhone experience. When we launched Palringo for the iPhone, we said that our vocal IM functionality would be added imminently. We've kept the promise we made to the thousands and thousands of iPhone users who downloaded Palringo and made us one of the most popular free applications from the App Store".

Unlike the above-mentioned push-to-talk services (Verizon and Sprint), Palringo is entirely operator-independent and works on almost every cell phone released in the last two years, according to the makers.

"Some of the big carriers tout their PTT services, but they have the 'carrier barrier' limitation of locking their customers into their networks and only the handsets the carriers support," Ritz stated. "That sort of lock-in is a 20th century business model and it doesn't wash with savvy mobile users today."

Palringo is free to download and use. Visit the App Store to get it for your own handset.