Most of the people who need to make an international call from the United States to England are British expatriates who are calling back home. A majority of English migrations to the states occur for work purposes. In this increasingly global economy, partnerships between companies in both countries are growing, and executives travel back and forth to meetings, or simply move to the US here for years.
The best way to call internationally, especially if you are calling from one landline to another, is definitely to use phone cards. You will get a terrible surprise on your phone bill without one, sometimes hundreds of dollars in charges from your service provider. This is because you are calling outside your service area.
A phone card calls a local number- inside your service area- which then independently connects you to the international phone. No one can overcharge you for being good and staying within your local call range!
There are no surprise bills with phone cards because you fill and refill them like you would a prepaid cell phone, so you are always in control of the amount you spend.