Your corporate telephony environment is a combination of Lync 2013 and traditional Private Branch Exchange (PBX). Currently, the company has 2,000 users. The company expects to add an additional…

Your corporate telephony environment is a combination of Lync 2013 and traditional Private Branch Exchange (PBX). Currently, the company has 2,000 users. The company expects to add an additional 2,000 users during the next year. On average, the company has 20 percent of its users on a public switched telephone network (PSTN) call at any time. Currently, users make three or more PSTN calls per hour, and it is expected that the new users will make a similar number of calls. The circuit count for light, medium, and heavy traffic is shown in the table below:

You need to recommend the number of ports required by the PBXs for simulated current usage and the expected growth. How many ports should you recommend?