here's a tip about how to get free service for your smartphone

req's:
-android phone
-google account
-house phone (only needed for setup)
-WiFi Connection
-$3.99 on a card

pros:
-its free in the sense that you are not paying a cellular provider
-free text
-free calls
-Free Data (since you're using wifi)

cons:
-cannot be used when wifi is not available
-voice sometimes lags during voice calls
-cannot send/recieve picture messages unless its through email

::you may use either a brand new or existing android phone but brand new phones will need to bypass the initial setup (at least i had to when using my moto droid) then put their google account in manually through settings.

::on a computer, login into google voice and get a phone number. you must use an existing number to activate google voice. i used my house phone to do so.

::from google voice settings forward calls to google chat.

::use android market to download an app called GrooVeIP for $3.99

::enter in your google credentials to GrooVeIP

for more info check out these guys

alternatively if you dont want to be stuck using wifi all the time, look into some data only plans from your cell phone's cellular provider.