SMS Opt-in / consent from your customers is required, per the FCC.
Whether gathering consent verbally, during in-person membership registration, or by including auto opt-in language in your member agreement -- giving your customers the choice to opt-in to SMS blasts is best practice and essential to SMS marketing campaign success.
Though not currently required in Blaze, you may wish to include verbiage at the end of SMS blast copy that notifies the recipient of opt-out protocol.
(i.e.: 'text stop to opt out')
Whether or not you choose to include opt out instructions in your sms blast, Blaze follows sms blast industry standards for U.S. short codes (i.e.: STOP) and will send a compliant response if an opt out (or back in) reply is sent. (see examples below)
Note: certain words are not allowed to be sent via mass text/SMS. See the list of known words here.