Its free, but...

Google voice is a free app that allows you to have an extra number on your phone. It is very useful when you many to make and receive calls. Its use for messaging is very limited: it turns itself off at the worse possible moment, it is very slow to send and receive messages, and the attachments you send are sometimes not received on the other end, without letting you know about it.

There are other apps that do the same thing a lot better, only that you have to pay for them. But, when something sounds too good to be true...

Miamibiz about Google Voice, v2.8