You should not use SMS text messages as a 2FA to access your exchange accounts. Even if you do not keep any money on an exchange, if someone successfully takes over your cell phone number, and can learn your password, or access your email account, they can drain your linked bank account, or max out your credit card associated with/linked to your Coinbase/exchange account.

Google authenticator is far superior in terms of 2FA. In laymens terms, it uses a private key plus the current time to calculate a code good for a limited time. As long as your physical device is kept secure, and malware free, an attacker will be unable to obtain the private key to calculate the 2FA codes.