Originally Posted by Boult

Although those who are using My IP Relay Number won't be charged for any calls but those who calls to your "My Ip Relay Number" will be charged because the area code is not a toll free area code number.

This from their FAQ page;

Do I get billed for receiving a call on my wireless device?
You will not be billed for an incoming call. Your regular device service charges apply.

Does the person calling me get charged a fee?
Depending on where the voice caller is calling from and the number you are assigned, there may be a long distance toll charge.