Most brands collect phone numbers the wrong way. They throw up a pop-up, offer a weak discount code, and call it a day. Then they wonder why their SMS call list growth stays stagnant.
Growing a high-intent SMS list isn’t about tricking people into subscribing. It’s about giving them a reason so good they’d feel stupid saying no. This list covers 15 underrated strategies—including one that tripled a brand’s opt-in rate overnight.
Here’s what you’ll get:
- Incentives that actually work (no, 10% off isn’t enough).
- Smart automations to capture numbers effortlessly.
- A wild SMS strategy (nobody talks about #3) that builds a list faster than ads.
TL;DR – How to Grow Your SMS List
- Get explicit consent – Follow the Telephone Consumer Protection Act (TCPA) and set clear expectations for subscribers.
- Use pop-ups wisely – Mobile-friendly pop-ups and landing pages boost SMS sign-ups without overwhelming customers.
- Separate email & SMS opt-ins – Asking for both at once adds friction; keep them separate for higher conversions.
- Checkout is prime real estate – Offer exclusive promotions or exclusive access to encourage opt-ins.
- Leverage QR codes – Place them on product packaging, in-store displays, and emails for easy SMS subscriptions.
- Promote SMS-only deals – Use social media, email lists, and paid ads to reach a wider audience.
- Collect numbers through multiple touchpoints – Use order confirmation texts, thank-you messages, and live chats.
- Allow SMS restock alerts – Let customers opt-in for text alerts on sold-out products instead of email.
- Engage shoppers in person – Ask for sign-ups at brick-and-mortar stores via cashiers or checkout posters.
- Host SMS-exclusive contests – Incentivize sign-ups with giveaways, polls, and referral programs.
👉 TxtCart automates SMS marketing, making it easy to engage more subscribers and maximize conversions.
1. Get Permission First & Set Expectations
Talk about using clear policy language, maintain (Telephone Consumer Protection Act) TCPA compliance, and setting expectations of what users can expect with SMS.
Here’s an example of Forver21, a clothing brand collecting phone numbers of mobile users along with consent while setting expectations clearly.
Read next: TCPA Compliance Guide for SMS Marketing [+ Checklist]
2. Implement a Pop-up
Pop-ups have an 80% reach when it comes to getting your message across! And we’re guessing you already use them for sharing offers, exclusive promotions and updates with your online and email subscriber list too. How about you use pop-ups to collect phone numbers?
There are many ways in which you can use pop-ups on landing page to collect mobile numbers:
- Share an offer or a discount with an SMS opt-in invitation
- Ask your site visitors to subscribe to your SMS list through a pop-up
- Show pop-ups to shoppers who visit your website on mobile phones. That way you’d be targeting shoppers who are more likely to shop on their phone!
An example of an e-commerce brand effectively using website visitors using mobile-specific pop-ups is Mylk Plus. They display a pop-up on landing page of their mobile site offering a 10% discount to website visitors who subscribe to their email list. This strategy targets mobile shoppers, encouraging them to engage with the brand directly from their devices.
3. Don’t Ask for Email & SMS At The Same Time
As an online store, collecting emails is a no-brainer. But a common mistake people make is they ask for the customer’s email and phone number in one go on the same form.
To the customer, this is too much “work” and friction, as Max Sturtevant puts it, Founder of Well Copy, an email marketing agency for eCommerce brands.
“Changing this alone will boost your list growth 50%+,” he says
Read next: The Complete Guide to SMS Marketing for Shopify Stores
4. Ask customers to join at checkout
The checkout page is prime real estate for marketing lists collecting phone numbers—buyers are already engaged and trusting your brand enough to complete a purchase.
How to Get More Sign-Ups at Checkout
- Show social proof – A simple SMS program of “Join 50,000+ shoppers for exclusive deals” boosts credibility.
- Offer an incentive – A real perk (think 15% dollar off discounts, early access, or VIP-only drops) makes opting in a no-brainer.
- Make it seamless – One-click opt-ins reduce friction and increase conversions.
An ecommerce brand that’s doing this is Express Insider. Here’s what their SMS pop-up at checkout looks like:
With TxtCart, you can easily capture phone numbers at checkout, ensuring every high-intent shopper has the chance to subscribe.
Read next: How to Collect Phone Numbers for SMS Marketing
5. Use QR Codes to Make Signups Easy
QR codes remove friction—one scan of short code and they’re in. They’re fast, convenient, and work across both SMS marketing channel – online and offline touchpoints.
Where to use QR Codes for SMS signup form
- In-store displays – Capture foot traffic while they browse.
- Product packaging inserts – Turn one-time buyers into repeat customers.
- Pop-ups & posters – Add them to event booths, checkout counters, or email footers.
The key? Pair real value in your QR code with a compelling reason to sign up. No one scans a random code—give them instant value (discounts, VIP perks, coupon codes or early access to exclusive access).
- Talk about the benefits of qr codes
- Different ways to put QR codes in front of customers (ie., popup, product packaging inserts, etc)
One brand that do this is Nike, a $51.46 billion sneakers brand. It uses QR code on its in-store displays that you can use to buy products straight from phone.
Read next: 8 Hacks to Increase Your Ecommerce Sales Today (Easily)
6. Promote SMS-only discount on social media
Turn your social media platforms into SMS subscriber magnets. Run campaigns that offer SMS-only discounts—shoppers drop their number, and you send them exclusive deals. Simple.
How to get more sign-ups:
- Offer a deal tied to SMS – Exclusive discounts, VIP access, or limited-time promotions.
- Use multiple marketing channels – Promote on Instagram, Facebook, TikTok, email, and your website for maximum reach.
- Make the CTA clear – Use direct messaging like “Text DEAL to 12345 for 15% off” to drive action.
Here’s how JUDY, a brand that provides emergency kits to protect you from natural disasters and home agencies:
Read next: eCommerce Upselling: Strategies, Benefits, and Best Practices
7. Collect phone numbers via different communication messages
Every message you send—order confirmations, SMS marketing messages, thank-you emails, and pop-ups—is a chance to grow your SMS list. Instead of treating them as one-time interactions, use them strategically.
Ways to collect numbers naturally:
- At checkout – Ask customers to opt-in for order updates via SMS.
- In thank-you emails – Add a CTA like “Get exclusive discounts—sign up for text alerts!”.
- Through pop-ups – Show a real-time offer when shoppers browse your store.
Here’s an example:
Read next: The Best Time to Send SMS Marketing Messages
8. Grow your SMS list through email campaigns
Email is still the channel that drives top performance. Why not use it to grow sms messages list via sms marketing platform to increase your SMS messages list?
Those who have joined your email list have already shown interest in your brand or products – why not invite them to recieve text messages as well?
9. Allow shoppers to subscribe to restock alerts
Stockouts don’t have to mean lost sales. Let shoppers subscribe to restock alerts via SMS so they’re the first to know when an item is back. While most brands use email, SMS alerts are faster and more direct—test SMS-only sign-ups first, then offer email as an option if needed.
How to automate restock alerts:
- Use a restock alert app – No manual tracking needed.
- Swap ‘Buy Now’ for ‘Notify Me via SMS’ – Capture high-intent buyers instantly.
- Collect real subscribers – Only engaged shoppers will share their phone numbers.
This ensures you’re building an authentic SMS marketing list—full of people who actually want to hear from you.
Here’s an example:
10. Offer something exclusive to SMS subscribers
People love exclusive perks—it makes them feel valued. Give your SMS subscribers VIP access, early product drops, or special discounts to keep them engaged. These offers should be SMS-only, making subscribers feel like they’re part of an exclusive club.
Why exclusivity works:
- Shoppers crave special treatment – VIP deals keep them engaged subscribers.
- SMS feels more personal – People check their phones 24/7, making SMS a direct way to connect.
- It drives sign-ups – Exclusive text alerts encourage more people to fill SMS sign up form.
Using SMS platforms to deliver timely, personalized offers taps into shopper psychology—and grows your list at the same time.
Read next:
- How to Send Personalized Text Messages that Sell.
- Conversational SMS Guide: 15+ Best Examples, Uses, & Tips
11. Invite contest participation only via SMS
If you’re a marketer, you’d know the power of contests to engage consumers. Contests have a 3.7% higher conversion rate compared to other engagement methods. So, it’s time many marketers to get smart – use contests as a way to grow your list.
What should you do?
- Run contests, giveaways, polls, and other interactive activities that can be joined only via SMS
- Invite shoppers to participate, but exclusively through their phone numbers
For example, “Enter your phone number to win a voucher worth $100.”
Here’s another example:
Read next:
- 11 Types of Discounts to Use in SMS Marketing campaigns to drive more sales
- How to Create Gift Cards on Shopify that Sells like Crazy
12. Through Facebook and Instagram ads
When Redbox, an online DVD rental store, ran a promotional campaign that asked their Facebook followers to give text messages with a shortcode for a discount, they received over a million text messages from their customers.
The above case study is a great example of the potential of social media ads to grow your SMS list. You too, can a great tool to increase your SMS marketing list through your social media channels.
How?
- You can make use of your social media as one of the SMS channels to run ads that help collect phone numbers
- You can power your ad with a chatbot with automatic SMS opt-in
Here’s an example of a Facebook ad that uses click-to-call ads:
13. Create opt-ins for mobile devices
Mobile shoppers are already engaged—so why not turn them into SMS subscribers with SMS marketing messages? When visitors access your store on mobile, show them a landing page or pop-up inviting them to join your SMS subscriptions.
Why Mobile Opt-ins Work:
- Higher conversion rates – Mobile shoppers are more likely to buy, making them ideal SMS subscribers.
- Instant engagement – Pop-ups and one-click opt-ins make sign-ups effortless.
- Boosts sales – SMS keeps shoppers in the loop about exclusive offers and restocks.
💡 Pro Tip: Keep it simple.
For example, your mobile pop up could read: “Hi there! If you’d like to receive updates on exciting discount offers and sales, text ‘YESME’ to 72213.”
How Grunt Style do this:
Read next: 16 Ways Fashion and Clothing Brands Use Shopify SMS Marketing to Drive Sales
14. During live customer support chats
Shoppers often need quick answers before making a purchase. Live chat, chatbots, and customer support apps provide instant help, but they’re also an opportunity to grow your SMS list and to get the most out of SMS list building efforts.
How to collect phone numbers through live chat:
- Answer questions & offer value – Help shoppers while naturally prompting them to sign up.
- Automate responses – Set up chatbots to collect SMS subscriptions for restocks and promotions.
- Keep it seamless – Make sharing a number as easy as one-click opt-ins.
Here’s an example of how this works in action:
Hi! Got any queries related to our product?
Yes. I am looking for a pair of shoes that are out of stock.
Sure. We’re going to restock all the out-of-stock items soon. Could you please share your contact number so that I can intimate you once the items are restocked?
Sure. Here’s my contact number: 683927293
Read next: Retail SMS Marketing: Strategies, Best Practices, and Examples
15. When shoppers buy from your brick-and-mortar store
If you have a brick-and-mortar store, you have a great opportunity to grow your SMS list. Because here, unlike online stores, you can engage with your customers one-on-one.
You can ask them in person to share their contact number for updates and offers from your store. Conversely, you can even display posters on your payment counter that invite them to text a shortcode to subscribe to the SMS list.
Here’s an example:
Once you sign up at TxtCart, you can personalize the automations to send right messages to the wider audience, at the right time.
Read next: Best SMS Marketing Examples to Supercharge Your Marketing Campaigns
16. Ask for referrals
92% consumers trust referrals from people they know. Use that trust to grow your SMS marketing list by turning your existing subscribers into brand advocates by referral text message marketing.
How to Get More SMS Referrals:
- Send text alerts – Ask loyal customers to refer friends in exchange for reward points or exclusive perks.
- Incentivize new sign-ups – Offer free gifts or dollar off discounts for every successful referral.
- Automate the process – Set up a referral system that keeps growing your SMS list on auto-pilot.
As your SMS subscriber list increase, segment your subscribers to keep messages relevant. Sending valuable content in text marketing program keeps them engaged—so they don’t unsubscribe faster than they signed up.
Here’s an example:
Hey Ryan, thanks for being a loyal customer to <brand name>. We’d love for you to join our referral program. Invite a friend to subscribe to our SMS list and win 10% off!
Read next:
- 5 Ways to Use SMS Marketing for Customer Retention in 2025
- 20+ SMS Templates for Feedback, Surveys, and Review Requests
How SMS Subscriber Acquisition Is Measured
Growing an SMS list is great—but is it actually working? These key metrics help you track what’s driving (or slowing down) your SMS subscriber growth.
- SMS Subscriber Growth Rate – Measures how quickly you’re gaining new SMS subscribers. Compare new sign-ups to your total list size over time. Slow growth? Your strategy may need a tweak.
- Opt-ins – Tracks the total number of sign-ups. Identify where they’re coming from (pop-ups, checkout, social) to refine your strategy and focus on what works best for mobile users.
- Opt-in Confirmation Rate – Not everyone who signs up confirms their subscription. A low rate may indicate unclear follow-ups or second thoughts—improving this can lead to higher conversions.
- Opt-outs – Tracks subscribers leaving your list. A sudden spike could mean your messaging frequency or content isn’t resonating. Monitor trends to prevent unnecessary churn.
- Opt-out Rate – Percentage of subscribers who opt in but later unsubscribe. High numbers could mean texts are too frequent, irrelevant, or not valuable enough. Keep this low by refining messaging and frequency.
Read next:
- The Ultimate Guide to SMS Opt-in for 2025 (Tips + Examples)
- 10 Best SMS Flows to Boost Your Shopify Store Sales
Grow Your SMS List With TxtCart
Congratulations—you now have a toolkit of strategies to get more SMS subscribers like a pro. From using mobile-friendly opt-ins to leveraging in-store promotions, you’re equipped to turn every interaction into SMS subscriptions opportunity. Here’s a quick recap of the key takeaways:
- Use incentives like exclusive discounts and early access to encourage sign-ups.
- Optimize touchpoints such as pop-ups, checkout, and live chats to collect numbers effortlessly.
- Leverage cross-promotion through email and social media to grow your SMS list.
With TxtCart, you can simplify and automate your SMS marketing messages. From seamless checkout opt-ins to personalized messaging, TxtCart ensures every subscriber gets the right message at the right time—helping you grow a high-intent list without the guesswork. It’s time to turn casual shoppers into loyal customers, one text at a time.
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