@ex200167 since the VoLTE, it seems like we need to include the 1 to call more often
Also, while you think you don't have to include 1, some dialer like Google dialer will actually add the 1 behind the scene
No worry about including 1, it won't make a a Lond distance call and starting charging. We (at least most of us) have Canada wide calling, so, it won't give you extra charges
@ex200167 - message is usually connected to a network issue or number out of service.
Perform a Reset of your device's Network Settings and see if that helps. This also resets Wi-Fi networks and passwords, cellular settings, VPN and APN settings, and connected Bluetooth devices that you've used before.
To Reset Network Settings, begin by opening the Settings app. Next, tap General -> Transfer or Reset iPhone -> Reset -> Reset Network Settings. and enter your passcode.
Your iPhone will reset network settings and restart itself.
Find and tap Settings > System > Advanced > Reset options > Reset network settings.
Check for outages in your area: