The easiest and best way to dial toll-free numbers in most of the world is to make use of Skype through your computer. If you do not have it , here is the link to install
www.skype.com The call through Skype is still toll-free and you don't have to have credit to make the call.
Procedure :
1. Select to make a call on "call phones " in Skype
2. Change the nationality flag in the call box
3. Enter the complete tollfree number
4. press "Call"