The recommended way to build an SMS database and prompt customers to opt in is by activating SMS as a transactional communication point. Transactional communication includes purchase confirmations, receipts, shipping notifications, appointment reminders, and many more. Customers typically opt into these transactional communications by entering their phone numbers at an eCommerce checkout point including a website form or a mobile application. Transactional SMS campaigns are a great ‘in’ with customers because, unlike email, the SMS channel guarantees immediate engagement and communicates urgency (e.g. Your order just shipped. Track it here!) Once part of the transactional communication stream, an SMS subscriber is familiar enough with the brand and its SMS program to start receiving promotional SMS campaigns.
In terms of opting out, it’s a best practice to ensure, at the point of subscribing, what type of messages and via what channels customers are going to receive and what are the Terms & Conditions of these messages. It’s always best for marketers to have a centralized preference center where their subscribers can manage their communication preferences and indicate the type of content they would like to receive, the frequency they want to receive communications in, and the channel(s) they prefer to be reached on - SMS, email, push, social, direct mail, or all of the above.