Using QOS capabilities, network managers can connect VOIP phones directly into a VLAN switch and configure the switch to reserve sufficient network capacity so that they will always be able to send and receive voice messages.
Step-by-step explanation:
Basically VOIP means voice over the tcpip address. Each phone set is are connected with network socket and connected to VLAN switch. Advantage of VOIP no need to have separated land line connection.
End user can call either local or international by network call. Network administrator cans also general report on call logs and control the end user on local or international calls.
Due to VOIP an organization avoids telephone bills which are routed on network (internet).
All VOIP is service oriented by server. QOS Service is used to operation from windows server.