This paper intends to present some important theoretical and practical results that we faced during setting up a VoIP (Voice over Internet Protocol) server with the well known open source VoIP server Asterisk. For a fully functional voice exchange we require to set up a server based on Asterisk, connecting clients to the server with the help of soft/hard phones and then comes the configuration aspects of the soft phones with the server. Here in our implementation we have connected the clients to the server with the help of SIP protocols.