Many VoIP business providers have a smartphone plan that uses your data plan, which is cheaper than your minute plan, to connect wireless to their network rather than their cellular towers. But is it really cheaper? And will using up all those minutes sap up your precious data?
Fortunately, this is all data that can be easily calculated. Most plans allow for 1GB of data, so we’ll look at how long you can talk with only 1 GB. The G.728 VoIP codec uses 4.096 kilobytes every second, or 0.24MB every minute. Do the math, and you can talk for 4,166 minutes, or 69 hours, every GB.
What if you want to use video chat? One second of video using h.264 uses 64 kilobytes every second, or 3.75 MB every minute, so if you exclusively video chat, you can get 266 minutes, or about 4 hours and 45 minutes, for one GB.
Remember, also, that you will not be using any of that data if you are using Wi-Fi. A second thing to keep in mind is that VoIP codecs will adjust with the availability of your network. If your network is spotty but not enough to drop the call, your call quality will go down momentarily. When you have a better connection, you will have higher sound quality, at the (small) cost of using more data.
When you add it all up, you’d have to be making hundreds of calls, and not even be on Wi-Fi when you make them, to go over your allotted data. By every reasonable definition, VoIP uses a tiny fraction of your data each month.