Toll Free Numbers are opposite of how normal numbers work, in this the customer calling do not have to pay a penny but the client who is receiving the call needs to pay accordingly. So basically bigger companies opt these numbers so that people are able to call them and ask their queries but side wise they should not pay any penny for calling them.
Here is a full list of all those numbers and that too classified in categories to which they actually belong, so just search the company and check the number you need to call.
