VoIP call

There are three different ways to make a VoIP call:

ATA/IAD

The easiest way to make a VoIP call is to use an Analog Telephone Adapter (ATA) or Integrated Access Device (IAD). These devices are connected between a telefone and a PC or Internet connection. The ATA/IAD converts the analog speech signal to digital data packets that can be transfered over the Internet.

IP telephone

IP phones look like ordinary telephones, but instead of an RJ-11 connection (the conventional POTS phone connection) they have an RJ-45 ethernet connection. Because of the standard ethernet connection, the IP phone can be connected directly to a router. The required software and hardware are all in the phone itself. Therefore there is no need for a pc. The only thing you need is a broadband Internet connection.

PC to PC (Voice over DSL)

Using special free software which can be downloaded from the Internet you can make phone calls to any PC that has the same software installed. Examples of such software are Skype and Messenger. With this software installed you can make worldwide PC to PC phone calls for free. The only thing you need is a broadband Internet connection, plus microphone and speakers attached to your PC's sound card.