The Ooma Linx Remote Phone Jack is a wireless accessory that allows you to use your primary phone number or as a second line for your Ooma Telo/Office Wi-Fi. This black unit features wireless capabilities and is secure and Wi-Fi friendly. It also has a pass-through mode for fax machines and other devices, making it a versatile and convenient addition to your home networking setup. With its DSL/Phone (RJ-11) interface, this Ooma Linx model is a reliable choice for expanding your home phone setup.