1-700-555-4141
Just found out about this number. It will tell you who the long distance carrier is for the number you are calling from, and is no charge (although other 700 numbers ARE NOT!).
Also, appears that 500 and 700 numbers can be setup by your phone provider as ‘forwarding’ numbers. You create a 500/700 number and pay them a fee for the service. When someone calls the number, they pay for the call, but they reach you at whatever number you’ve defined as the target phone number. It appears some phone companies even allow a list of prioritized numbers to try, so it will automatically work its way down the list.
How did I find out about this? Just signed up for a Rogers bundle which includes relatively inexpensive long distance. They gave me the number, telling me to call it to confirm that my long distance was switched. Before calling the number, I did a search on Google, and eventually found a site that talked about this number (it was on the second page of my ‘700 phone number’ search).