Have cell service but can't send or receive SMS texts-fixed

​My wife's iPhone 11 recently had an issue which resulted in her cellular network connection being lost for several days.  The connection is back now and she can make and receive calls but she can no longer receive SMS text messages.  iMessage works fine since it uses wifi.  She needs SMS to text with Android users and to receive texts that are required for accounts that have two-factor authentication enabled.  Any thoughts on how  cell service can work for calls but not for SMS?  No settings have been changed.​