UC is the integration of many forms of communication, including fixed and mobile voice, and Internet based applications such as email, IM, VoIP, presence...you get the idea. While this sounds complicated, the goal of UC is to simplify communications so that everyone can be reached anywhere, anytime, via the mode of communication that's most helpful for them (for instance if I'm in a meeting, I'll get your email on my cell phone, and you'll see I'm unavailable for a phone call on the presence application running from your desktop).
Unfortunately there are those among us leveraging the "hype" surrounding UC to scare end users into believing that something that seems so complicated must inherently be insecure. This is not so.
The first step toward deploying any UC architecture is to plug your phone into the Internet. VoIP is the stepping stone to UC, and even smaller businesses can implement VoIP using very easy-to-install SIP trunking equipment. This is also a cost-effective way to adopt VoIP and, ultimately, UC applications.
With the right SIP trunk trio in place -- ITSP, IP-PBX and SIP-enabling edge device - you can be up and running with a SIP trunk in a matter of minutes (we did it in 15 at the ITEXPO in Miami this past January). Most ITSPs are offering SIP trunk services now; if you need help, contact your local VAR (one focused on convergence solutions).
As for VoIP, security for Unified Communications can be achieved with the right equipment protecting your network. Maximize the security benefits of SIP with the right edge device - far too often, in SIP trunking solutions we see enterprises connecting their PBX directly to the Internet which jeopardizes their network security.
The edge device should not only ensure security, but also handle interoperability issues among all of the various equipment, service providers etc. Incompatibilities can become security risks quickly. Addressing them proactively drastically reduces your exposure.