IP – telephony gets more speading in our modern life.However it can be realized that it has only few persons.We offer you recognition its existing more closer. In a general way, IP telephony it is a technology using IP as main mean transmission voice. For definition of this phenomenon is used also aberration VOIP,which deciphering as Voice over IP, otherwise Voice up protocol Internet (IP). For transmission of signals from one phone to another phone necessary special setting IP - subnet.
This settlement is realized by helping broadcast from one type of network to another type of network IP – subnet or another called name is IP services which it can connect one side of the phone line to another end which can connect another line of the world phone line, another can be connected with internet with any connection to internet. Telephony signal with subnet is numbered, squeezed, separated into packets and it’s sent through IP network accourding fixing by using protocol TCP/IP. Then the signal passes through one of subnets where can be reform in telephony.