This phone number cannot be used to verify the account

Hello,
I have created a new account for business purposes, using the same cellphone number for verification I use on an existing gmail account. I have used the account and everything was fine, but the next day when I tried signing in, it prompted me to verify my account, Google saying: detected unusual activity on account.
However, when I enter my cellphone number, it prompts: "this phone number cannot be used to verify the account". Like what the fluff?? Can anyone please help?