When you're looking at the return on investment (ROI) for a VoIP solution, one of the most difficult things to sort out is labor, perhaps second only to quantifying impact on user productivity. Partially, this is because of marketing from the manufacturers that leaves the promise of convergence -- which implies fewer people -- in the back of your mind. But integrating and supporting a new technology almost always means more work, not less.
In a medium-sized organization where you have a modest IT staff on salary, a VoIP deployment probably won't result in additional headcount, only in additional hours worked for the existing staff. Since they're usually salaried, there's really not much impact on ROI. But in a larger organization, you often have to deal with fluctuating resource requirements during the deployment and the ongoing need for support afterwards. Which brings us again to the question: "Will I save money on labor or not?"
Assuming there's no project at all to maintain the status quo, any project costs you have would be compared to $0. So obviously, you'll be motivated to minimize the labor budget -- but take care, as the real key is in the project execution. If you run into integration trouble or technical difficulties, re-working can push out your ROI in a hurry. To get a realistic number, it's best if you take the cost of your project's risk mitigation strategies into account when calculating ROI for the project.
This component includes supporting the voice network, soft switches and gateways. In theory, you could potentially save money by consolidating the people who manage the data and voice networks into one group. However, for lots of different reasons (not the least of which is organizational inertia), this is rarely realized. If you think you'll save money by consolidating engineers and administrators, be prepared for an elevated level of critical scrutiny.
User support and "moves, adds, changes"
Understand that you're not doing less labor, so much as distributing the labor to be done. For example, if you're moving a department from one area of your building to another, traditionally, the "phone guy" would have to go move the phone from one desk to another and then make changes on the cross-connects, and possibly update some configuration on the PBX for 911. With VoIP, you still have the option of letting the designated "phone guy" move the phone, but now you can also have the user move the phone. Since the Ethernet MAC address on the phone doesn't change, the only labor necessarily performed by administrators is updating the location for 911 services. Thus, the question becomes, "how much are you spending today for moves, adds and changes?" Tom Lancaster, CCIE# 8829 CNX# 1105, is a consultant with 15 years experience in the networking industry, and co-author of several books on networking, most recently, CCSPTM: Secure PIX and Secure VPN Study Guide published by Sybex.