However, productivity improvements is a "soft" value and very difficult to calculate, which keeps many IT professionals from even trying. One of the big challenges is how you take a users normal work process and convert that into dollars, measure the increase in activity, convert that to dollars and measure the difference. Often, the benefits tend to vary widely from user to user making it even more difficult to measure.
Recently, I've run into a number of companies that have been trying to use non-financial metrics as a way of measuring value. Non financial information can be used as a way to augment the limited financial metrics companies have to prove the shift to UC does have business value.
In a recent Yankee Group survey, we asked which of the non financial metrics companies use to measure the ROI of UC and the results can be seen below. 
As can be seen from the chart, many companies are looking to UC do think that will lead to productivity improvements but not necessarily be measurable in dollars. However, you could measure the value of providing better access to colleagues by measuring how quickly routine tasks get completed. I admit, these are still "soft" benefits but they are things that can be measured and then converted to something financial, if needed.
The one area of enterprise that has mastered this is the call center industry. In the call center, the key performance indicators (KPI) are metrics like call duration, customer queue times, hold times, how many calls per day an agent can handle, etc. This is so mature in this industry that most seasoned call center managers can tell you exactly what kind of impact to the business each of these metrics has. I believe that this type of non financial measurement is key to proving the value of UC and I've seen a few, ad hoc examples already.
* A nationwide fast food chain deployed IP based voice to the drive through stand and route calls to people not at the restaurant to help with overflow and language barriers. The metric of "drive through wait time" was used to justify the value. * A hospitality manufacturing organization measured that 11% of a sales persons day was spent waiting and 16% on sales administration. By enabling the worker to communicate in real time when mobile, they were able to allow the user to complete many administrative tasks while waiting, lowering the overall idle time. * A manufacturer of home appliances used six sigma quality measurements to understand how the overall quality of products was improved by using new collaboration tools
* A large hospital digitized all patient records and provided tablets and WiFi phones to its clinicians to give better patient care. The hospital measured human error rate reduction as a way to measure value. The hospitals insurance costs were actually reduced because of this.
I have a number of other examples in different verticals where the company used a metric that is key to their business, measured it, deployed UC, measured again and was able to come up with a "value" that was meaningful to the organization. The KPIs used from one company to another and one group to another will vary in the organization, but they do exist for all organizations. The key is to find the KPI that has enough value to the enterprise that the deployment of UC becomes a "no brainer".
For readers currently evaluating UC or have a deployment under way, there are a few things you can do to help justify your purchase.
First, this may be difficult but critical but work with your business leaders to develop KPIs for the high impact groups in the organization. There's no need to do this for all user but the high impact ones are a minimum.
Second, locate a group of users within the larger group that can be beta users to measure the KPI before and after implementation. Finally, and again, this may take help from the business unit leaders but try to understand the business process well enough that you can calculate where UC will have the biggest impact. If this can be done, funding will be much simpler than without it.
