It may not be the only way but the one i'm most familiar with is through the parrot mki9100 or mki9200 hands free kit. You'd need the kit and an SOT Lead. The SOT lead depends on what sort of audio system you have, half amp'd, amp'd or bose amp'd. But this obviously is a stand alone unit that works seperate to the RNS-E which isn't what you said, but i'm just giving you an option cos i know it works.