First of all, Contoso decided to order the required server hardware that was recommended in the system integrator's design proposal together with the Microsoft Lync architect. The server hardware was a mix of "physical" hardware and virtualized servers. The virtualized servers would host basic infrastructure and Lync services in a virtual environment.

Next, both the IT department as well as the user can start preparations for the real integration. A 50-member department in the main office was changed to act as the pilot group for the first stage in the UC pilot. These 50 users were made to have their existing PBX phone switched off. The telephone numbers of these pilot users were routed through a S2M (ISDN) connection between the Siemens HiPath Routed 4000 PBX system and the SIP gateway which is connected to the Lync Server (Mediation Server).

The preceding graphic is an example for VoIP Gateway (AudioCodes); connection between Lync, PBX, PSTN (telephony network), and/or...