Build Communications with Twilio

SMS notification systems, WhatsApp chatbots, voice IVR menus, video calling apps, two-factor authentication, contact centers, appointment reminders, order tracking—any application requiring communications. Twilio provides APIs; you build the logic. Common uses: marketing, support, authentication, alerts, and conversational commerce.

Use the Messaging API: get a phone number, call messages.create() with 'to', 'from', and 'body' parameters. Handle delivery status via webhooks. For bulk, use Messaging Services for phone number pooling. Consider compliance: opt-in requirements vary by country. Test in trial mode before going live.

Messaging API: simple send/receive for SMS/MMS/WhatsApp. Conversations API: multi-party, multi-channel chat with history, participants, and webhooks. Use Messaging for notifications and simple 2-way. Use Conversations for support threads, group chats, or persistent chat requiring context across channels.

Apply for WhatsApp Business API access via Twilio. Get approved message templates for outbound (24-hour session window). Use the same Messaging API—just use 'whatsapp:+number' format. Handle inbound via webhooks. WhatsApp requires Facebook Business verification and template approval for proactive messages.

Twilio Verify is a turnkey 2FA solution: handles code generation, delivery (SMS/voice/email/authenticator app), and verification—you just call APIs. Use Verify instead of building 2FA yourself to avoid security pitfalls, rate limiting, and carrier filtering. Includes silent network auth for seamless verification.

Use TwiML (XML-like markup) to define call flows: <Gather> for input, <Say> for speech, <Play> for audio, <Dial> for transfers. Host TwiML on your server or use Twilio Functions (serverless). Studio provides visual IVR builder. Integrate speech recognition and AI for conversational IVR.

Flex is a fully programmable cloud contact center—customize everything via React and APIs. Unlike rigid solutions (Zendesk Talk, Genesys), Flex lets you build exactly what you need. Best for: companies with developers who want control. Consider turnkey solutions if you want out-of-box features without customization.

Twilio targets 99.95% API availability (approximately 22 min/month downtime). Enterprise plans include contractual SLAs with credits for violations. Twilio uses multiple carriers for redundancy. Check status.twilio.com for real-time health. For mission-critical apps, implement fallback logic and monitor delivery rates.

Use toll-free or short codes for high-volume (better deliverability, lower per-message cost at scale). Leverage Messaging Copilot for smart sending. Consider regional numbers for local rates. Use webhooks efficiently—don't poll. For 2FA, Verify is often cheaper than building on Messaging due to included retry logic.

US 10DLC registration is required for A2P (application-to-person) SMS. Register your brand and campaign in Twilio Console. Provide use case details and sample messages. Approval takes days to weeks. Non-compliance results in blocked messages. Use short codes or toll-free for high-volume pre-approved use cases.

Yes, integrate with OpenAI/Claude for conversational SMS bots or voice AI. Use <Gather> with speech recognition, send transcription to LLM, respond with <Say>. Twilio's Media Streams enable real-time audio for advanced voice AI. For SMS, parse incoming messages and generate LLM responses in your webhook.

Studio is Twilio's visual workflow builder for IVR, SMS automations, and chatbots. Drag-and-drop widgets for logic, no coding required. Integrates with Functions for custom code. Good for non-developers or rapid prototyping. Export to code when you outgrow visual limitations. Included in Twilio pricing.