At one end, the cable will plug into the headphone jack of your mobile device, and at the other, it will plug into the auxiliary input for your car’s audio system. The easiest way to connect a phone to a car stereo is through an auxiliary cable. 1. Connect using an auxiliary cable – a cheap, fast, and quick method. Looking for an easy solution? If so, you’re in luck! In this article, we’ll tell you about four of the easiest ways to connect your phone to your car stereo, and give you simple instructions for doing so. Having trouble playing music from your phone though the speakers in your car? Maybe you’re tired of listening to the radio, or can’t seem to find a song you like.