Yes but you will have to add the data plan again which has gone up to 34.99. The data plan for your dash (if you have one) will not work.
This, and the outrageously outdated hardware was the reason I left the Sidekick. He will be missed (his keyboard was second to none) but I can use the 100MB plan with unlimimited texts on my iPhone and after I changed the APN, T-Mobile doesn't track my data usage so it is technically unlimited.
Enjoy though, the Sidekick 3 was a cool phone when I had it a few years back.
When our 5 powers combine, we summon Earth's greatest champion: Captain Planet.
Driver picks the music. Shotgun shuts his cakehole.