Article discusses our established Service Desk, which was created to help and facilitate the work of a wide sector of users. To reduce costs in small and large institutions rather than traditional PBX solutions, the use Voice over IP (VoIP) is offered. Then you can use open source software Asterisk branch. This supports both conventional phones and the phones working with SIP. The advantage of this solution is easy to maintain and modify all of its properties to the customer. These requirements may be very specific and that their implementation requires an effective combination of open-source tools. One of the many frequently used service is an answering machine. Asterisk offers this feature, of course, and we created a tool that offers users the administration machine, plus the possibility of redirecting the phone when the user is not available, that the user does not miss important calls or let the caller record a message on the answering machine.