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1. Basics of SMS marketing
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1.1 What is SMS marketing?
SMS marketing is the practice of sending promotional or transactional text messages to customers on their phone numbers, with their consent. Since SMS marketing is not dependent on an internet connection and doesn’t require any app installation, it enables brands to reach customers anywhere in the world.
However, it doesn’t mean that businesses can spam customers with back-to-back texts. In 2026, you need explicit consent from your prospects and customers.
1.2 What are the different types of SMS marketing?
SMS marketing is the practice of sending promotional or transactional text messages to customers on their phone numbers, with their consent. Since SMS marketing is not dependent on an internet connection and doesn’t require any app installation, it enables brands to reach customers anywhere in the world.
However, it doesn’t mean that businesses can spam customers with back-to-back texts. In 2026, you need explicit consent from your prospects and customers.
- Promotional SMS: Texts built to drive a purchase, such as discounts, flash sales, new arrivals, and seasonal campaigns.
- Transactional SMS: Messages tied to an action a customer already took, such as order confirmations, shipping updates, delivery alerts, and appointment reminders. These are not promotional and have different compliance rules in most regions.
- Conversational SMS: Two-way texts that let a customer reply, ask a question, or continue a conversation instead of just receiving a one-way broadcast. Brands use it for support, order changes, and guidance.
- OTP and authentication SMS: One-time passcodes and verification codes sent to confirm a login, a payment, or an account change. Delivery speed matters most for authentication texts, since a slow OTP defeats the purpose.
- Automated or triggered SMS: Messages sent by a workflow rather than a person, such as cart abandonment, back-in-stock alerts, price drops, and win-back campaigns. These are triggered based on customer behavior.
- Alerts and notifications: Time-sensitive updates like service outages, appointment changes, or account alerts, sent because the customer needs to know now, not because a campaign happens to be live.
Important note
Promotional and transactional SMS generally follow different consent rules. In many regions, including under the US TCPA, transactional messages don't require the same opt-in as promotional campaigns, but if a transactional text includes a sales pitch, it can trigger promotional consent requirements. Keeping the two message types separated protects deliverability and keeps a program compliant.
1.3 What does SMS marketing look like in practice?
Promotional
"Flash sale: 30% off everything for the next 6 hours. Shop now: [link]. Reply STOP to opt out."
Transactional
"Your order #4521 has shipped and should arrive Thursday. Track it here: [link]"
Conversational
Customer: "Can I move my appointment to Friday?" Business: "Sure, Friday at 3 PM works. See you then!"
Automated / lifecycle
"Hi Jane, you left running shoes in your cart. They're still available. Complete your order here: [link]"
1.4 Why SMS marketing works?
Open rates for SMS are around 98%, well above email's typical 15 to 25%. The average reply to a text also comes back in about 90 seconds, far faster than typical email response windows. These factors make SMS one of the fastest ways to reach someone who has already said yes to hearing from you.
What are SMS opt-ins and opt-outs?
An opt-in is a customer's explicit permission to receive SMS messages from a business. An opt-out is a customer's request to stop receiving them. Both are the foundation of a compliant SMS program, since sending marketing texts without consent, or continuing to send after a customer opts out, is what triggers fines and carrier blocks in most regions.
- Opt-in: Consent collected through checkout, a website popup, a keyword texted to a shortcode, a loyalty signup, or a QR code. A clear opt-in states what the customer is signing up for and how often they will hear from the brand.
- Double opt-in: A second confirmation step, usually a reply text, that verifies the number belongs to the person who opted in. Some regions and carriers require it before promotional sends begin.
- Opt-out: A customer request to stop receiving messages, most often triggered by replying STOP, UNSUBSCRIBE, or CANCEL. Once received, the opt-out has to take effect immediately and apply across every campaign sending to that number.
- Implied consent: Consent inferred from an existing relationship, such as a recent purchase, which some regions accept for transactional messages but rarely for promotional ones. This varies enough by region that it should never be assumed without checking local rules.X
