By Ian Bush

PHILADELPHIA (CBS) – A new iPhone app ranks cell phone carriers to help you pick the best plan whether you’re at home, work, or on your commute.

It’s called CarrierCompare. App maker SwayMarkets founder Amos Epstein says with one touch, “it runs a quick test on the network where you’re standing on the phone that you’re using, compares it to any other carriers in that area, and then it will rank the carriers for you so you can see which one will deliver you the best service at that time of day and at that location.”

The free app checks signal strength, download speed and Internet response time. Each test is recorded and sent back to their servers, and it’s that crowdsourced info that shows you whether Verizon, Sprint, or AT&T works best.

“It’s totally unbiased data. It’s not coming from the carriers and they have no say in how we rank things, so it really is a clear view of how things are going to perform.”

He says it’s more precise — and more useful — than the wireless companies’ coverage maps. Of course, the usefulness of the app increases with the number of other iPhone owners who give it a whirl, so you have nearby data sets to compare with your own.

Epstein suggests testing the iPhone in different spots where you’ll give it the most use, or to use the app on a friend’s phone to help inform your buying decision.