To listen to every NFL game streaming online or on your phone you'll want to get NFL+ which you'll be able to Listen to Live home and away radio broadcasts online for every NFL regular season game.
You might be able to listen to some NFL games using the iHeartRadio app, however the NFL has restrictions on streaming games live. NFL Monday night games broadcast on Westwood One radio stations can often be streamed live.
Another really good iPhone radio app for finding and streaming some NFL games live is the TuneIn Radio app.
Using the TuneIn app, you can do a search for your favorite football team, and you'll see a list of stations streaming the games live. Overall, TuneIn Radio app is a bit better than the iHeartRadio app.
Or search for your NFL teams flagship radio station, to see if they are streaming games.