Unified would be nice, but to cut costs we are using a blend of technologies to get the same effect. For my PBX type service, I am using a hosted service from Grasshopper. It gives me auto attendant and voicemail boxes. Each extension (and voicemail box) can be configured separately to ring another number (we usually use Skype-In or a cell phone - there are a lot of options here) and if there is no answer, take a voicemail. Voicemails are then delivered to me in 2 ways: via email as an MP3 attachment and also as an MMS message to my cell phone. Since all staff have a Skype number and account, we constantly utilize this software for conference calling, video calls (this works with 2 people only), , and instant messaging. Skype is great for its hands-free capability by using our PCs. We also have two fax numbers, one from MyFax.com and the other provided free with out account from Grasshopper. We use the MyFax.com fax as a general fax for our company and it emails to a public folder on my mail server that is monitored by staff and distributed appropriately. The other fax line from Grasshopper.com emails to a separate public folder available only to executives and hr.
So, with multiple services we were able to get the features of unified communications (voicemail, email, faxes all in one inbox) without the upfront cost of an all-inclusive system. This was a great solution for us when we were only 5 employees. Now that we've grown to 10, we're having some management issues on managing all of the services we strung together. Usually, once its set up its fine but getting new employees set up is becoming a pain since we have different people in charge of monitoring and managing the different services. Eventually, we will probably move to an all-inclusive system if we continue to grow.
A couple of my clients use the ShoreTel suite of products and I'm pretty happy with those for unified communications. If we grow like we have been, we will be looking into a system from either ShoreTel with paid support or we will do a roll-your-own system from someone like TalkSwitch or even the open source Asterisk.