How to hook my IPhone directly to car speakers?

I want to hook my phone directly to car speakers. Is there a device that will plug into the headphone jack then into the speakers?

Auxiliary port and cord

Some car stereo systems have an aux input somewhere near the buttons. If yours has one get an auxiliary cable and plug one end in that and the other end in your phone.

if you can't find he auxiliary hole then yours dosent have it and you can't do it =(

hope this helps!

By doing your mom

You need to install and auxiliary audio input adapter to your factory radio that way you can plug your iphone to the headphone jack, the phone don't have enough power for the speakers,
http://www.oemautosound.com/c-20-auxiliary-input.aspx

or you can buy an iPod interface, this adapter needs to be purchase for your vehicle brand and model, they are not FM or universal
good luck

http://www.oemautosound.com/c-19-car-ipod-iphone-interface.aspx