I have replaced my GoPhone with a Platinumtel phone for data.  For the most part, I am happy with it, but I occasionally will need data outside of Platinumtel/Sprint coverage, so I am filling that gap with an Airvoice SIM.  I just activated it today.  I have to spend at least $10 every 90 days to keep it active.  I put the SIM in my former GoPhone, which is an unlocked Pantech Link.  I then called Airvoice customer service and they downloaded the settings to my Pantech phone, so I can now use it for data.  I was very impressed with the Airvoice customer service.