WhatsApp ?

[flan_taster]

Can anybody explain to me how WhatsApp really works and whether it can replace SMS texting ?

See: http://www.whatsapp.com/

How it works

WhatsApp Messenger is a cross-platform mobile messaging app which allows you to exchange messages without having to pay for SMS. WhatsApp Messenger is available for iPhone, BlackBerry, Android and Nokia and yes, those phones can all message each other! Because WhatsApp Messenger uses the same internet data plan that you use for email and web browsing, there is no cost to message and stay in touch with your friends.

In addition to basic messaging iPhone, Android, Nokia and BlackBerry WhatsApp Messenger users can send each other unlimited images, video and audio media messages.

[Enrique]

Hi flan_taster,
Your friends will have to download the app as well for it to work.
There many be a small fee after a year

"Switch from SMS to WhatsApp to send and receive messages, pictures, audio notes, and video messages"

[blondie]

The messages are sent via internet and it is more like a chat style messaging system,than texting. It´s the same type of thing that Blackberrys have with BBm messaging,which again is "free" but you pay for internet instead - Yoigo for exaple offer 500meg for 8 euros a month.