Voice over Internet Protocol ( VoIP ) is a protocol optimized for the transmission of voice through the Internet or other packet switched networks , IP networks(hired line, frame relay, xDSL)and it is also improved for communication through fax. By this way, especially the communication with telephone /fax to reach long distances gets cheaper or becomes free to pay. Because of occupying only 6.3 Kbps (64 Kbps for stable telephones) it causes no slowness. In VOIP devices applications you can integrate VOIP to the system in a short period without making any change in IP network devices and PBX station. VOIP devices are not depended on a private station or a Router. It can perform with any Router or Station. This is a very important factor that lessens the cost of investment of VOIP.