One of the best that things I like about my Sony Tablet S is the ability to use it in conjunction with my Google Voice account. I'm able to initiate and receive voice phone calls over WI-fi without any kind of cellular connection. I purchased a $4.99 app called Groove IP which allowed me to take advantage of this extraordinary Google service on my tablet.
Video - How to Use Your Android Tablet to Initiate and Recieve Voice Phone
Google Voice offers free calling within the United States along with caller ID, call screening and voice mail. Voice mail messages are sent through to my Google account as well as translated to text and forwarded to my cell phone. Calls actually ring through to my cell phone as well. When I use Groove IP on my tablet, I can use my Bluetooth earpiece and receive phone calls. using my Google number with no cellular charges. Aside from the initial cost of the Android App. this entire process is currently free! This is the second year in a row that I've been using a Google Voice number for many of my vendor contacts and now with the ability to use my Sony Table S, it's that much better.