SMS alert require the phone number to be in international format.
When entering the phone number on SMS field, add the country code with the phone number.
For example if you are in Australia [+61] and your phone number is 0412 345 678, enter the number in this format => +61412345678.
SMS services is an Add-on and it must be active per device. To check if your device has the SMS Add-on active, go to the Frigbot's page and scroll the page all the way down and click on 'Frigbot Add-on'.
The page will expand showing all the add-on items for your device.
SMS must be showing "Active". If it is not, please edit the edit and switch the status to "ON" and save