The SMS percentage that is displayed in the Notify Me® module includes the total number of unique subscribers who have a phone number both set and confirmed, across all mailing lists of all Notify Me modules and are subscribed to at least one SMS list that is not deleted.
Please contact your CSM if you would like to increase the total number of subscribers possible.
This count is displayed as a percentage of the value set in
NumSMSSubscriptions value can be found in the Module Parameters of Notify Me:
This total count also includes SMS subscriptions for those categories that have since disabled the
Allow SMS property. For example, if a user is subscribed to the list "ABC" for SMS, and the list "ABC" category is modified and SMS availability is removed those SMS subscriptions still count towards the total percentage displayed.