Some of the benefits we receive from our internal Microsoft Unified Communications deployment include:

•Reduced cell phone bills.
•Reduced long-distance costs with toll bypass.
•Reduced PBX maintenance at Catapult’s headquarters.
•Elimination of PBX maintenance at branch offices.
•Elimination of “physical” phones in all of Catapult’s cubicles.
•A highly mobile workforce that can make & receive calls anywhere (office, client, home).
•Notification of missed calls and voice mails in an email inbox, including email-enabled cell phones.
•Complete log of all calls and voicemails forever.
•Centralized IT can now perform all add/moves/changes with familiar Active Directory and Exchange tools.
•Drag & drop call transfer & conferencing.
•Ability to “see” who is on a conference call.
•Ability to escalate from instant messaging, to desktop sharing, to a UC call in just a few clicks.

Full case study is here:

https://www.catapultsystems.com/CatapultDownloads/CatapultCaseStudy_CatapultUC.pdf