If you need to use Skype or some other program for talking with computer, please ask to the sysadmin for the headset. Skype is installed on every linux workstation.

VoIP means Voice Over IP Protocol and it's just another acronim to indicate the possibility to use Internet like we use the phone: start the connection and talk with someone else in whatever part of the planet.

There's some technical difficulties that prevent this as the TCP/IP protocol wasn't designed to carry voice communications, but only data. today this difference is quite inexistent, but some difficulties remains for users withe reduced bandwidth. Until now the use of VoIP meant the necessity to install some program in out computer and start some strange sequence of operations to be able to connect with someone else. Fortunately now there's something standard and also stand alone device that work mainly like the phone at home. these phones are like computers, but they can do only one thing: permit to you to talk to someone else.

At the moment there's 2 different standards mainly used by these devices and also by programs running on standard computers: Skype and S.I.P.

Skype is the first program that really had a spread diffusion and that permitted to lot of people to start talking communications. It's based on a standard proprietary that is an evolution of the former Kazaa protocol, used for the peer 2 peer sharing files. this program and the protocol is a “de facto” standard and is used by millions of computer users. using a program or a phone device that support this protocol, you can talk with someone else for free or spending very little. In order to use Skype, you have to subscribe to the service and you'll receive a nickname that can be used by others to call you. You can also call and be called from normal lines numbers, but you must subscribe and pay an extension of the service.

S.I.P. is the standard “de jure”, it's the specification that all providers and producers of VoIP devices must follow in order to generate a “compatible” device that can interconnect with others device on the Internet. The S.I.P. protocol is well supported where there's large bandwidth, but differently from skype is not usable free of charge. differently also from skype is the fact that you use SIP phone mainly to connect to the standard voice line. after the subscription you'll receive a telephone number that others can use to call you, no matter what kind of device (VoIP, analog, program) they're using.
In the major part of the occasion you can receive the communication for free, but if you want to call someone you have to pay a subscription. Almost in every case the subscription is less costly that the one you have using your standard voice line/phone.