Typically, Duo SMS (text) code delays are due to poor cellular signal, Duo text service outages, and cellular service outages. These issues typically resolve themselves on their own.
DO NOT repeatedly try to send more text codes if you do not receive the first few you tried. Each resend invalidates the the previous codes. Only the most recent requested code will work. Repeated failed login attempts can lead to your account being locked requiring support to unlock your account.
SMS codes are the most unreliable multifactor authentication method and pose other security risks. SMS Codes are no longer supported for logins to NC State Services through Duo. You are required to set up a supported Duo login method.
If you need further assistance, you can contact the NC State Help Desk by submitting a request in the IT Service Portal or calling 919-515-4357 (HELP). You can also visit the OIT Walk-in Center.