Us citizen otp not working form dir 3 kyc

Hi Friends

I needed to know for a US director's OTP mobile phone shall i enter the phone number as

001 314 331 1234 

+1 314 331 1234

1 314 331 1234 

Because i entered 001 314 331 1234 and the OTP did not work, meaning the US director did not receive the OTP. Can you let me know the right format to use to receive the OTP on the US director's phone. 

thanks

VJ