Telephone and cell companies have popularized “unlimited” calling plans, and customers love them. There is no watching the clock, and checking the number of minutes used.
One company that advertised unlimited calling is Vonage — the leading voice over Internet protocol (VoIP) company. Part of a commercial they ran in the past said:

The fine print is inconsequential for purposes of this story, but refers in part to the fact the only certain countries were included, and maybe not to cell phones in all countries.
Vonage’s website confirms that calling is unlimited to 60 countries:

Lo and behold, the company sent this letter to one customer claiming that he used too many minutes on his unlimited plan.
Dear XXXXX XXXXXXXX,,
We appreciate your business and thank you for using Vonage for your phone service.
In order to provide the best value to all our customers, we track usage of Vonage residential calling plans. At the time of signup, you agreed to the Vonage Terms of Service (TOS), which includes usage guidelines for normal residential use. If you would like to review the usage guidelines, please see sections 5 and 10 of the TOS.
We have observed usage on your account, 1234567890 , which is not consistent with normal residential use. Specifically, your account shows irregular patterns of use and/or international-minute usage that is more than twice that of our heaviest users.
At this time, you can remain on your current plan, but your usage will need to be changed to fall within normal residential use guidelines; this usage would generally not exceed 3,000 international minutes per month. [emphasis added] As another option, you can switch to a different calling plan, or you can disconnect your service without penalty.
For additional information about your options please respond to this email and one of our associates will be glad to assist you.
Regards,
Vonage Customer Service
101
When at Vonage’s terms of service, one learns
*MOUSE PRINT*
5.4 Inconsistent with Normal Use.
If you use the service, any feature or the device in a way that is inconsistent with the normal use for your service, feature or plan, you will be required, at Vonage’s sole discretion, to pay the rates for the service, feature or plan that would apply to the way you used the service, feature or device, or terminate the plan. For example, if you subscribe to one of our residential service plans, and your usage is inconsistent with normal residential use, you may thereafter be required to pay our applicable, higher rates for commercial service for all periods in which your use of our service or the device was inconsistent with normal residential use. Unlimited voice services are provided primarily for continuous live dialog between two individuals. Lack of continuous dialog activity, unusual call patterns, excessive conferencing or call forwarding, excessive numbers and/or consistent excessive usage (which may also apply to features such as Directory Assistance) will be considered indicators that use may be inconsistent with normal use, or that impermissible use may be occurring and may trigger an account review or further action by us. We may determine inconsistent use based on material deviations from the usage patterns and levels of most of our customers using the same and/or similar service plans, features or devices
In summary, they say if your use is inconsistent with normal residential use, they can charge you commercial rates, put you in a higher priced plan, or terminate your service. Nowhere do they establish a specific cap of 3000 international minutes.
If you think about it, 3000 minutes a month is only 100 minutes a day — just over an hour and a half of calling. I could easily imagine someone with loved ones overseas talking that amount of time.
This is yet another example of companies that like to advertise “unlimited” services of one kind or another, but in fact they do have limits that are not clearly stated upfront.