How to collect phone numbers for sms marketing?

Lead Generation
1

Hey everyone, I run an e-commerce store on Shopify, and I want to get into SMS marketing. The problem: I have zero phone numbers. I have a solid email list of about 8,000 subscribers, but no mobile number list for marketing at all.

Here’s what I need help with:

  • What’s the most effective way to collect phone numbers from a website?
  • Are there good phone number collector tools or apps for Shopify?
  • How do I do this legally? (TCPA, GDPR, etc. genuinely scare me)
  • Free vs. paid, what’s worth spending on?
  • Can I use my existing email list to get contact numbers for marketing?
  • What are the biggest beginner mistakes when building a mobile number list for marketing?

I want to do this 100% above board. No buying lists, no shortcuts. Clean, opt-in subscribers only!!

We’re on Shopify and Klaviyo, a small team, with a limited dev budget. Most articles I find are too surface-level or just trying to sell me a specific tool. Honest advice from people who’ve done this would mean a lot. Thanks :folded_hands:

2 Likes
2

@michelle-brnt, the fact that you’re asking about compliance before you’ve collected a single number already puts you ahead of most people. :grinning_face_with_smiling_eyes: I’ll give you the full picture.

First, reframe what you’re doing

You’re not “collecting phone numbers.” You’re getting express written consent from a real person to send them commercial texts. That distinction changes how you design every opt-in touchpoint. When you think of it as consent, you naturally write better copy, give better incentives, and build more trust, and those things also convert better.

Two consent types exist. Express written consent is required for promotional messages; the subscriber explicitly opts in via a form, checkbox, or keyword. Implied consent (from an existing transaction) only covers things like order confirmations. Don’t rely on it for marketing messages, even in jurisdictions that technically allow it.

Your website is where most numbers will come from

Having monthly visitors is your biggest asset right now, but it’s doing nothing for SMS yet. Five channels are worth your attention:

  • Checkout opt-in. This is the most underused method in e-commerce, and it’s not close. Your customer is already typing in their phone number for shipping updates, their wallet is open, and purchase intent is at its highest. Klaviyo’s Shopify integration handles this natively. The checkbox must be unchecked by default. That’s a legal requirement in most jurisdictions, and the right approach regardless.
  • Exit-intent and timed popups. A well-built SMS popup can convert visitors. The offer has to be worth something; “subscribe for updates” gets ignored. “Get 15% off plus early access to restocks” gives someone an actual reason to hand over their number.
  • Embedded footer forms. A static, always-visible form in your footer won’t hit popup conversion rates, but it’s always there. Low effort, low friction, adds up over months.
  • Dedicated sign-up landing page. Create a landing page that actually sells the value of your SMS list: what subscribers get, how often you text, and what kind of deals. Drive traffic from email, Instagram bio, and paid social.

Your email list is worth more than you think here

8,000 subscribers who already trust your brand. That’s a real head start!! A focused SMS acquisition campaign on that list can move a great amount of them to SMS.

The sequence that works: Email 1 introduces the SMS program with an offer they genuinely can’t get anywhere else. Email 2 goes out three days later with social proof and a deadline. Email 3 is the last-chance send. Don’t link to your homepage; send them to a landing page built specifically for the SMS opt-in. The conversion difference between those two destinations is significant.

:police_car_light: I THINK IT’S REALLY IMPORTANT: Don’t import phone numbers you collected for other purposes. A customer who gave you their number at checkout for shipping notifications didn’t consent to promotional texts. Legally and ethically, that consent doesn’t transfer. Always collect fresh, specific SMS consent, every time!!

Free vs. paid - the honest version

Most of what I just described costs nothing beyond your existing subscriptions. Checkout opt-in is free. Footer forms and landing pages cost zero to build.

Where paid spend actually pays off: running Meta or TikTok ads to a dedicated SMS sign-up page. With a strong offer, you can acquire subscribers for $0.50–$1.50 each. :upside_down_face:

3

As a growth marketer at Popupsmart, building SMS lists through on-site popups is often treated like a solved problem: add a form, offer a discount, and expect results. In reality, the difference between a popup that captures phone numbers and one that gets ignored comes down to a handful of critical decisions that are frequently overlooked.

What makes phone number popups different from email popups

Phone numbers carry more perceived risk than email addresses. Your visitors know that handing over a number means texts in the same inbox as messages from their family and friends. That’s a different psychological threshold than an email address, which people hand out freely and filter aggressively. Your popup has to clear a higher bar, and most don’t, because they’re built exactly like email popups.

The three failures I see most often:

  • Triggering too early. A page-load popup fires at the worst possible moment: before the visitor has seen anything, formed any opinion, or built any trust with your brand. They came to browse gear, not fill out a form. Exit-intent triggers work better for phone number collection because the visitor has already spent time on your site. They’ve looked at products. The popup lands when there’s something to reference, not in a vacuum.
  • Offers that don’t match the ask. A 5% discount might work for email. It doesn’t work for a phone number. The channel is more intimate. The offer needs to reflect that with 15-20% off a first order, free shipping for life, and early access to limited stock drops. The more specific the benefit, the better it converts. ‘Exclusive SMS deals’ is vague, while ‘Be first to know when it comes back in stock’ gives a clear reason to subscribe.
  • Copy that describes the form, not the outcome. “Sign up for texts” tells someone what they’re doing. It doesn’t tell them why they’d want to. Rewrite every SMS popup headline to lead with the subscriber’s benefit, not the mechanism. “Get 15% off your first order, SMS only” is a headline. “Join our SMS list” is not.

How to build an SMS opt-in popup that actually converts

This is the setup I’d configure for an SMS popup campaign:

  • Two-step form. Step 1 collects the email, and Step 2 collects the phone number. You capture the email even if they drop off, and completion on step 2 is higher because they’ve already committed once.
  • Exit-intent on desktop, scroll depth (50-60%) on mobile. Both target engaged visitors, not people who just landed.
  • TCPA disclosure directly on the form. Below the phone field, readable size and contrast: “By submitting, you agree to receive recurring automated marketing texts from [Brand Name]. Reply STOP to unsubscribe. Msg & data rates may apply.” The full requirements are covered in the CTIA Messaging Principles and Best Practices and the FCC’s TCPA guidelines. Both are worth reading before you go live.
  • Suppress after close (30 days) and after opt-in (permanently). Showing the form to an existing subscriber damages trust fast.
  • Target by page type. Product pages get the discount offer. Blog readers respond better to restock alerts and early access framing.
  • A/B test the offer, not the design. Offer size, offer type, and headline framing move the needle. Button colors may not.
  • Connect to your SMS platform immediately. The welcome text should fire within 60 seconds of form submission.

Why SMS subscribers are worth a more generous popup offer

Phone numbers are harder to get than email addresses, and worth more once you have them. SMS is a direct channel with almost no inbox noise. A text lands differently than an email buried under twelve others.

That’s why it makes sense to offer a more generous incentive on your SMS popup than you would on an email form. The popup that collects 300 phone numbers a month with a 20% discount will often outperform the one collecting 500 email addresses at 10%, once you run the downstream revenue numbers.

SMS popups are simple on the surface, but the details make a big difference. If you’re testing one, curious what’s been working for you.

​You can also check out our guide: “How to Create a Free SMS Popup for Your Website.”

4

Good thread. A few things from the original question still haven’t been answered: the legal side, keyword opt-in, and what tools actually exist for Shopify. Let me cover those quickly.

Compliance for SMS marketing

  • US (TCPA): You need express written consent before sending any marketing text. A checked box on a form qualifies. A phone number collected for shipping notifications does not. Violations are $500–$1,500 per message — not per campaign. Keep your checkbox unchecked by default, put the disclosure on every form, and ensure STOP actually works.
  • EU/UK (GDPR/PECR): Consent needs its own checkbox, can’t be bundled into general terms, and you need to be able to prove it if asked. If any share of your traffic comes from Europe, build to the GDPR standard. Meeting it covers you on both sides.

Three things that get stores into trouble: texting email opt-ins without separate SMS consent, pre-checked boxes, and missing or buried disclosure copy. All three are avoidable.

Keyword opt-in (worth setting up)

Your SMS platform gives you a short code or toll-free number. You pick a keyword, something short and brand-relevant, like VIP, DEALS, or JOIN. Promote it as: “Text VIP to XXXX for 15% off.” When someone texts in, they’re added to your list automatically, and your welcome flow fires.

Lower volume than a popup, but cleaner consent and better subscriber quality. Someone who texts a keyword chose to do it; that’s a different intent from someone who filled in a form to get a discount code. Good places to put it: site footer, packaging inserts, email footer, Instagram bio.

Shopify SMS marketing tools

For your setup, the honest answer is:

  • Klaviyo SMS — start here. Native Shopify integration, checkout opt-in included, email and SMS flows in one place.
  • Popup tools (Popupsmart, Privy, etc.) — sit on top of any SMS platform, give you form design control and targeting options.
  • Postscript — SMS-first, better segmentation, and A/B testing, worth it once you’re scaling. Adds a second platform fee.
  • SMSBump (Yotpo) — solid if you’re already on Yotpo for reviews or loyalty. Deep Shopify integration.
  • Attentive — enterprise pricing, overkill until you’re much larger.

Beginner SMS marketing mistakes worth avoiding

  • Sending too often: SMS isn’t email. 4-8 sends per month is the typical ceiling before unsubscribes climb. Every message should have a clear reason to exist.
  • No welcome flow: The first text after opt-in is the highest-engagement moment you’ll get. Don’t waste it on a generic confirmation. Deliver the incentive and set expectations immediately.
  • Collecting numbers before knowing what to send: I’ve seen stores go dark for months after building a list because they had no content plan. The list goes cold. Build the strategy before you turn on collection.
  • Not warming up a new sender number: Start with low daily send volume and ramp over 4-6 weeks. Blasting from day one can get your number flagged by carriers. Most SMS platforms handle this automatically, just flag that you’re a new sender when you set up. :smiling_face_with_sunglasses:

Get the consent mechanics right from day one, retrofitting compliance onto a dirty list is a much harder problem than building clean from the start.