The Federal Communications Commission published a tip sheet that explains how to make international calls from landlines, cell phones and VoIP phones.
HowtoCallAbroad.com is another helpful site that provides information on how to dial internationally from the USA, Canada, or from any other country.
International Phone Directories
Infobel World - A database of 500 million+ global residential and business listings.
Numberway - International white pages and yellow pages.
Using Your Cell Phone in a Foreign Country
The articles How to Use Your Smartphone Overseas from TripSavvy and How to Use Cell Phones Abroad from USA Today provide advice about how to use your cell phone while traveling outside the United States. For more information, consult your carrier's international calling web site: