You may use multiple telephones in one service address. Depending on your phone set and phone wiring set up at home - different configuration may be required.
If you are using 2 telephone set...
Our Analog Telephone Adaptor (ATA or voice adaptor) device that is required for Home Voice to work comes with 1 telephone port.
If you wish to have 2 phones to share the same line, you can do so by putting a small 2:1 RJ11 splitter in front of the ATA to connect multiple telephones. A splitter basically splits your phone line into 2 or more lines.
These splitters can be purchased from an electronic hardware store and it looks something like this:
If you already have a phone wiring set up in your home, with multiple phones already connected...
Instead of where all your phones used to receive their signals from (e.g. the phone port in the wall), insert the common phone plug into the ATA.
Do Note: In some rare cases, when cables are a bit old or degraded, or when some specific phone models are connected together, there can be a mismatch between the multiple phones and the ATA, causing problems like a lot of noise on the line. Most of the time there should be no issues though!