I have no experience with tablets in general, but a Google Voice account will give you texting ability (although I think you'll have to use your GV number as opposed to your regular cell phone number) and then GrooveIP will give you VoIP via that same GV account, when you have access to WiFi.
I have no idea if these will install on your tablet but the combo works great on my OG Droid and Droid Bionic phones.