Product Model H6100 Car Phone System Explain * Car phone system is compatible with car stereo and car computer to gain quality timbre, which supply guarantee safe phone communication, intuitionistic operation interface and perfect information service when you are driving. * Internal GSM wireless correspond module and antenna for your quality phone conversation. Function & Character * GSM 900-1800MHz double frequency networks (SIM card support required). * Offer easy installation and exceptional convenience, Auto-mute & switch detection controlling. * Internal Siemens module, easily communication at anytime and anywhere. * Automatically auto-mute & switch to enter talk mode when incoming or out-coming calls. After talking it will come back radio or music performance. * Automatically and hand answering optional. * Intelligent handset with key and LCD is available for talking and function setting. Mostly Parameter Working voltage 10-15V