Format of PIN Recovery Phone Number?

I’ve not found this elsewhere, hence my question, as I found the instructions upon installing the Anti-heft module a bit confusing:

If you have a phone in the US with a number such as 123-456-7890, and which requires a reading 1for calling that number as a long-distance call, should the number in the Avast! settings be entered as +11123-456-7890, where the +1 is the US international dialing code, followed by the 1 needed for domestic long-distance, followed by the phone number?

If not, then the rather obvious next question is, how should this be entered?

Hi,

it should be entered in a way your device can send SMS messages to it. I generally recommend using the most complete format possible so if you can send a message to +111234567890, that is the best format.

Filip