Let's Look at the Pros
Moving your voice communications to a VoIP platform definitely has many advantages. Some can provide costs savings, but by far the major advantages are realized in intangible ways.
1. No Long Distance. Every call you make within the US is completely toll free. You can talk to whomever you want, for as long as you want. So, internet phone is cool, isn't it?
2. Features. Find me or follow me, call routing, call parking, conference calling, mobile numbers, do not disturb, data integration to the display, unified messaging, soft-phone and many others are usually all included and are far more numerous than any PBX system can offer. You just need an internet connection to make free internet calls and a computer or a laptop as well.
3. Administration. Adds, moves, and changes can be handled by a single internal person, from a single location regardless of the size of your organization. Billing statements are greatly simplified as well.
4. Flexibility. Dynamic changes in your organization's structure, whether growing, downsizing or relocating, can all be addressed with little effort and at no additional cost. Internet phone is as simple as searching on Google.
5. Data Circuits. Voice circuits, usually ISDN, are widely available and known to be stable. However, their recurring cost is quite high. Data circuits, too, are also quite stable though recurring costs are lower than those of a full ISDN line.
6. Hosting. Many VoIP solutions offer hosting. In this scenario, you simply pay a regular monthly fee based on users, phones, bandwidth, etc. The provider manages and maintains all of the equipment at a single location. Your phones and computers connect via any internet connection.