US Toll-Free Numbers, those starting with 800, 888, 877, 866, 855, 844, and 833, are not "free." These numbers are free for callers, allowing for customers to contact a company without paying any long distance charges. The calls are however, charged to the owning company.
This distinction comes into play when trying to call US Toll-Free numbers from international phone numbers, as the call will be charged to the company as an international call. Some companies will allow these calls to connect, while others will choose to block international callers to prevent the international charges.
If you are trying to call a US Toll-Free number from an international number and cannot connect successfully (usually with a message stating "your call cannot be completed as dialed, please check the number and dial again"), please try to find the alternate contact number for the company.
Please note: The alternate numbers will allow you to contact the US-based company, but the international call costs will be charged to your account instead of the US-based company's account.