Summary: , you need an FXO and FXS gateway. Here are some diagrams to explain how this might work in different situations. Using VoIP for Telecommuting Workers (Local OR Long Distance) Workers who are telecommuting still want to and NEED to be connected to the company's phone system. Here's how this scenario works: An FXO VoIP gateway is connected to
Image Dimensions: 545 x 178
Image originally found here.