7 programmable memory keys extended model optional                                                                        7个可编程存贮键，可配扩展模块          Message waiting /incoming call indicator.        360度可视留言灯/来电显示灯         Adjustable Ringing volume        三档铃声及八级可调通话音量键         Desk or wall mount        桌面及墙挂式安装         Compatible with PBX        适合各类用户交换机,