VoIP is nice and cheap, that is why you see Google Voice and Skype become more and more well-liked in just a brief time. There are some limitations with the free government cell phone, some can only be used to call 911 for emergency, some only offers 63 or 200 free minutes each month. It will be a nice idea to use VoIP to make finer use of your government cell phone.
However you can not set up phone calls on VoIP via your government cell phones. The problem is data plan issue, most of the free government cell phone providers, like SafeLink, ReachOut, Assurance and others only serve phone call and some may have free message package. But none of them have data plan offers, if you are willing to pay for it, you may contact the phone service provider whether it is eligible to activate data plan in your mobile phone. Remember you may also need a