Viber !!!

[DC]

Just been told about this ,don't know very much about it. Could be worth a look. :-/

http://viber.com/

[Squashed_Fly]

Lookds similar to whatsapp....

[Goldie]

I have used Viber every day for the last 2 years. Fabulous app - much better than whatsapp and any other VOIP app too. Allows you to make free unlimited WIFI calls to any other mobile phone using Viber via WIFI and send text messages & picture messages........ around the world.
It's freeeeeeeeeeeeee too and syncs with your other contacts on your phone to tell you who uses Viber too.
Oh, and it's freeeeeeeeeeeeeeeeeeee (so long as you are using wifi)

Not sure you can get it for Crapberry Blackberry phones but its available on iphone and android

[Gooz]

I always use it, great abroad too with no international tarifs......... were all on it, and make sure we tell each other just to vibe us unless its an emergency.......... saved an absolute fortune, although it didnt too well in russia :)

[YMFB]

I'm on it and use it fairly frequently, it's not as popular as Skype but does have more of phone feel to it.