App says "Please enter a valid phone number"

[darangho]

While signing up the minitoring (Setting --> Monitoring), Ring app keeps asking to enter valid phone number eventhough it is a right number. (in xxx-xxx-xxxx format). Any idea why this happens?

The field only allows number (only number keypad shows up in the app and +1 is already pre-filled), so I don’t know why it complains. Any idea on how to bypass this?

[darangho]

Made it work through web browser, but problem still exists in Ring app.