If you are having trouble receiving SMS code, you can choose to reset SMS Authentication following below guide.
1. After entering user name and password, in the page ‘SMS Authentication’, please click “Phone number is unavailable?”
2. Choose the country where you are, enter new cellphone number and click "send verification code". Enter the verification code and click "Verify and Update".
3. If your Google 2FA authentication is activated, please enter the code to update cellphone.