If you would like to use a secondary phone number for Smart SMS marketing messages then you can add a secondary number in your Operator Customizations.
Please see this article on configuring the SMS Connect option for complete instructions on enabling SMS on your dashboard.
Why would you want to have 2 phone numbers? As an example, if a guest connects at a Hotspot and uses SMS to login or is required, they will receive a 4 digital code to enter and they will then be redirected. Most guests have no issue with this. However, if they THEN receive an SMS marketing message and they reply ‘STOP’, they will not be able to login at that location again because they would never receive the text verification message (Unless they happened to reply ‘START’ to the original phone number. So, it’s BEST to have a separate phone number for SMS Text marketing messages in case the guest does happen to reply ‘STOP’, they will still be able to login at another hotspot venue that uses the same phone number.