No you don't, though you can use any PC with speakers and a microphone attached to make phone calls.

If all you want to use for VoIP communication is your PC, then perhaps you will want to get some USB handset or just a plain headset with a microphone.

 

If you don't want your computer switched on all the time, then perhaps it's best to get a simple ATA (Analog Telephone Adapter) which is permanantly connected to the Internet through a router and subscribed to a VoIP Provider. These devices allow you to continue using your standard phone and you can make and receive VoIP and regular phone calls using the same phone. When selecting a device, make sure it does have a PSTN fallback.

 

Another alternative is a dedicated IP Phone, which, likewise, requires a subscription to a VoIP provider, who will then also provide the termination services to the public telephone network. Note: We do not recommend an IP Phone to be the only phone in the house, due to problems that may arise when dialling emergency numbers.