I'm trying to port my current toll-free number to Zendesk Talk and want to forward calls while the port is being completed. My current carrier told me I can't forward calls from my current toll-free to my Talk toll-free number. Why not?
Call forwarding from a toll-free number to another toll-free number often does not work due to the cost structure of the toll-free numbering system. When a call comes into a toll-free number, the owner of the toll-free number is responsible for paying the cost of the call.
In a calling scenario, when there are multiple toll-free numbers involved in the call chain, each party tries to pass off the cost to the other party, and often providers avoid this hassle by rejecting calls from other toll-free numbers. This behavior is inherent to the toll-free phone number system and is not specific to calls made with Talk toll-free numbers. Talk is not able to guarantee all toll-free to toll-free calls will complete successfully.
To forward calls in from your current toll-free number, you will need to create a local number in Talk and then use that number when forwarding calls from your current provider.
For more information about toll-free numbers, see the articles: Are there any restrictions or limitations with toll-free phone numbers? and Can I make outbound calls with my toll-free number?