OnSIP and PSTN Gateway customers dialing certain Canadian cell phone numbers get busy signals. These cell phone numbers are provided by Rogers Communications and one of their subsidiary company's, FIDO. The busy signal only affects callers who are not sending a caller ID. Make sure your account has a valid caller ID associated with it. In OnSIP, this can be accomplished via the web portal in the "User" tab (for individuals) or in the "Account" tab (for the entire company). For PSTN customers, this can be completed either on your PBX or in the "Configuration" tab in your web portal.