SMS, voice, and WhatsApp for your application. Twilio built correctly, not just wired in.
Twilio integrations for SMS notifications, OTP verification, appointment reminders, and voice calls require proper phone number management, opt-out handling, and the webhook patterns that handle delivery events correctly. We build Twilio integrations for production.
Application that needs SMS notifications, OTP verification, or automated voice calls — and needs it built reliably with proper opt-out handling and delivery tracking
SMS integration looks simple: call the Twilio API with a phone number and a message. Production SMS is more complex:
Number management. Twilio phone numbers have different capabilities and costs: local numbers, toll-free numbers, and 10DLC (10-digit long code) registered numbers for application-to-person (A2P) messaging. A2P 10DLC registration is required for most production SMS in the US — without it, messages are filtered by carriers.
Opt-out handling. SMS recipients can reply STOP to opt out of messages. Twilio automatically handles STOP responses and stops delivering messages to opted-out numbers, but your application needs to track opt-out status and not attempt to send messages to opted-out users.
Delivery webhooks. Twilio sends delivery status webhooks (delivered, failed, undelivered) for each message. Production applications need to handle these to track delivery status and detect failures.
Rate limits and queuing. Applications that send high volumes of SMS (appointment reminders, notifications) need to queue messages and send at Twilio's throughput limits, not in parallel bursts.
International considerations. International SMS rates vary significantly by country. Some countries have specific requirements for SMS sender registration.
Twilio integration with SMS, delivery webhooks, opt-out handling, and the phone number management that keeps sender reputation high
SMS notifications
Twilio SMS API integration in Next.js Route Handlers or server-side logic. Message templates with variable substitution. Scheduled SMS via background jobs.
OTP verification
Twilio Verify API for SMS OTP codes. Verification flow with code expiry and attempt limits. Alternative: Twilio Verify handles the code generation and validation, avoiding custom OTP implementation.
Appointment reminders
Scheduled SMS reminders triggered by calendar events or database records. Reminder cancellation when appointments are cancelled or rescheduled.
Delivery tracking
Webhook endpoint for Twilio status callbacks. Delivery status stored per message. Failed message alerting.
Opt-out management
Opt-out status tracked per phone number. Message sending blocked for opted-out numbers. Re-subscribe flow for users who want to opt back in.
One honest number to start.
Fixed-scope, fixed-price. The number below is the starting point — final scope is built from your brief.
Twilio integration with SMS, delivery webhooks, opt-out handling, and the phone number management that keeps sender reputation high
Three steps, every time.
The same repeatable engagement on every project. No surprises, no mystery, no billable ambiguity.
Brief & discovery.
We send you questions, then get on a call. Output: a written scope with every step, feature, and integration listed.
Build & ship.
Fixed schedule, weekly reviews. No scope creep unless you change the scope — and if you do, we reprice it transparently.
Warranty & retainer.
30-day warranty on every launch. Most clients stay on a monthly retainer for ongoing features and maintenance.
Why Fixed-Price Matters Here
Twilio integration scope is defined by the message types and trigger events. Fixed price as part of the application build.
Related engagements.
Questions, answered.
10DLC is the US carrier registration program for A2P (application-to-person) SMS. Unregistered sending leads to carrier filtering. Registration requires a brand registration (~$4/month) and a campaign registration (~$10/month). Registration can take 2–4 weeks for approval. Budget for the registration timeline.
Twilio has a WhatsApp Business API integration. WhatsApp requires a Facebook Business account and approval for the WhatsApp Business API. The integration is more complex than SMS and has different message type restrictions (template messages for outbound notifications vs. free-form in response to user messages).
Part of the application build. Full application from $25k. Fixed-price.
Tell Ryel about your project.
Describe what you’re building and what outcome you need. You’ll have a written, fixed-price scope within the week.