The messenger app Ping! is available on the iPhone AppStore since a couple of days now and is still free for the moment.

The difference between Ping! and other messengers is that Ping! transfers data through the push notification services of your iPhone and by doing so proposes a free alternative to your SmS service. 

You don't need to register In order to use Ping!. When launched the first time you simply choose a personal ID which will identify you on the network and which you can share with friends.

Ping!-IDs can be linked to address book entries. Messages are received instantly which means that it is quicker than sending an SmS too. If a message couldn't be sent directly, if the internet should be down or out of reach for example, the message will be stored until your iPhone connects back to the Internet again. The message will be then delivered automatically.

There is also no time limit to validity of messages compared to classical SmS services and even very long texts can be sent successfully. Only downside so far is that you can only send text and no pictures.

Ping! is a really great app based on a great idea. So download it as long as its free!