If the project will only contain numbers from one country, you can set the Dialing Country on the Project Details page (under Dialing & Recording). You would then import the phone numbers in the normal format for that country, and the system will validate them based on the specified country’s format.

If you have phone numbers from multiple countries with different formats in your file, then you will need to ensure that the numbers are preceded by the applicable country code. First ensure that on the Project Details page you have enabled Allow Dialing Multiple Countries. During the import process you will need to put a check on the option ‘Phone numbers start with Country Code’.