Error received when trying to set up 2-Step Verification

When trying to enroll in 2-Step Verification after entering a phone number you receive a code, the following message appears and enrollment cannot continue:

Sorry, we can't fulfill this request at this time. Please try again later or use a different phone number.

• Admin console
• Security
• 2-Step Verification

1. Use a different phone number to perform the enrollment.
2. Allow a period of 24 or 48 hours before trying to do the enrollment again to allow for the system to remove any security block due to multiple failed attempts. 

This message appears for two main reasons: 

1. The phone number used to initiate the enrollment has already been used on multiple Google accounts.
2. Due to local issues (browser, network, not receiving the correct code, etc.) the verification could not be completed and due to failed verification the system blocks the enrollment for a period of 24 to 48 hours.