Why SMS beats email for payment reminders
Email open rates for invoice reminders average around 20%. SMS open rates exceed 95%. The median time to read an SMS after receiving it is under 3 minutes. The median time to open a billing email (if it's opened at all) is 6-10 hours. For getting paid quickly, the channel matters as much as the message.
The other key advantage of SMS is that payment links work immediately. A customer who opens an SMS, sees the amount, and clicks a Stripe link can pay in under 60 seconds. The same customer who receives a billing email has to open it, find the link, click through, and then authenticate — multiple opportunities to get distracted and forget.
What makes an effective payment reminder SMS
The best SMS payment reminders have four elements: your business name (so they know who it's from), the specific invoice amount (urgency and specificity), a direct payment link (zero friction), and an easy opt-out or contact method (compliance and trust). Keep it under 160 characters if possible.
Example: 'Hi John — this is a reminder from ABC Plumbing. Your $850 invoice from Nov 3 is ready. Pay here: [link]. Questions? Reply or call 555-1234.' That's the whole message. No corporate jargon, no threats, no lengthy instructions.
TCPA compliance for business SMS reminders
The Telephone Consumer Protection Act (TCPA) governs commercial SMS. The key requirements for business invoice reminders: send only during business hours (8am-9pm in the recipient's time zone), honor opt-out requests immediately (STOP keywords), and don't use autodialer features that send the same message to thousands of recipients simultaneously.
Surety handles TCPA compliance automatically. Messages are sent during business hours, opt-outs are tracked and honored, and the system never contacts opted-out numbers again. You don't need to understand the compliance requirements — the tool handles them.
Combining SMS with voice follow-up for invoices that don't respond
For the 20-30% of overdue invoices that don't respond to SMS reminders, voice follow-up dramatically increases resolution. The combination of SMS (high reach) and voice call (high urgency signal) catches almost every collectible invoice.
Surety's automated sequence is designed around this combination: two SMS reminders with payment links, followed by an AI voice call from Remi for invoices still unpaid after two weeks. The voice call serves as the escalation signal — it communicates that this is a real priority, not just an automated message the customer can defer indefinitely.