If one of the reasons you are considering VoIP for your business is because the VoIP Provider offers Unlimited Calling, you need to pay close attention to the fine print.
Most VoIP phone service provider has a clause in their service agreement called a Fair Use Policy or FUP. Before accepting service, make sure this policy is something your business can live with.
What does a fair use policy clause mean to me?
Business VoIP Providers that offer unlimited calling for one monthly price are really not telling you the truth. These plans almost always include a fair use policy in their Terms of Service. A fair use policy sets a maximum amount of minutes per month you can call. Any calls above this amount will be metered and added to your bill.
The good news is that most VoIP companies will view your account in aggregate. If one of your users goes over the fair use limit, but the rest are under, they will allow you to share the minutes from your entire company, and if in aggregate, you are under the policy limit you will not be charged. Most businesses rarely exceed the fair usage limits on an aggregate basis. You just have to make sure the fair use policy includes the aggregate language.
The reason VoIP service providers in USA have include this Claus is because they price their service based on an assumption that on average, each VoIP broadband phone user will use a certain number of calling minutes each month.