The telephone set is the piece of hardware that is closest to the human being in VoIP. It encloses both input and output for voice, and is the main interface between the user and the technology. There are several types of phones you can use with VoIP:
You might have already invested much money on your existing phones you use over
PSTN/POTS. Yes, you can still use them for VoIP, if you are equipped with an
ATA (Analog Telephone Adapter).
The best phones you can use with VoIP are IP phones, also called SIP Phones. These are specifically designed to be used for VoIP, and they have
features and functionalities that other conventional phones don't have.
A softphone is a phone which is not physically one. It is in face a piece of software installed on a computer. Its interface contains a keypad, which you can use to dial numbers.
IP Handsets
An IP handset is another type of phone made for VoIP. It is not independent, in the sense that it is made to be connected to a PC, to be use with a
softphone. An IP handset resembles a portable phone, and is equipped with USB cables for PC connection. It had a keypad for dialing numbers. IP handsets are also rather expensive.