Let the components of your VOIP system. Once you decide which VOIP provider to use, you get a VoIP adapter box, also known as an ATA box. This table is the size of a deck of cards and is the 'intelligence' behind VoIP. A cable box that connects to an alternative decision-ATA to your router high speed internet and standard RJ-11 from your phone connects regularly at the other end of the ATA box.
Ok, some of you say you have a problem, since your modem high-speed Internet a shot on him and it is where you connect your computer so you can get online. Yes, it's a problem, but not great. You will need to go to Best Buy or Radio Shack or a similar place and get a HUB. The best way to think of this as an extension cord for your modem high-speed Internet. You put the hub into an electrical outlet and you can then run a cable from the hub to plug your modem high-speed Internet. Now you can connect your computer to one of the connectors on the hub (you will probably have about 3 or 4 of them) and also plug the cable from your VOIP ATA box into an outlet on the hub. Before leaving Best Buy and Radio Shack, so make sure you have cables with RJ45 connectors at each end - one goes from the center of your modem and another password for your VoIP ATA box to the hub.
Now with your VOIP ATA box connected to the hub or directly into your modem high-speed Internet, if you had an extra connector on it, you just connect your phone in the traditional standard RJ-11 connector on the ATA box, and you are good to be done.
But what about VOIP phone use through the house not attached to the room with ATA box and a modem high-speed Internet? You have several options here. You can use a cordless phone when you connect the base unit to the VoIP ATA box, and then you're ready to go. I would recommend a cordless phone that is in the range from 5.8 GHz to give better coverage.
If you want to have multiple phones in the house, I recommend getting one of these multi-unit configurations of wireless phones. Some can accommodate up to eight phones with the same base.
There are places online that will explain how to connect the VoIP ATA box external wiring to the telephone system at home to the RJ-11 connectors that you have in each room can still be used. Although this is possible, not recommended. There are many stories of people who have flown ATA box and / or full telephone wiring in your home because they were not sufficiently familiar with the electrical load requirements of implementing a system like that. Unless you're an electrician or telephone company repair, this approach is likely to cause more problems than solutions.