feat: add sms skill + 5 SMS platform integration docs (#307)

New skill: skills/sms/ - SKILL.md (336 lines, under 500 limit): strategy, when SMS beats email, compliance overview, sequence types, copy guidelines, platform selection, measurement, common mistakes - references/compliance.md: TCPA, A2P 10DLC, EU GDPR, CASL, Australia, opt-in disclosure templates, STOP/HELP response templates, audit checklist - references/sequence-templates.md: full copy templates with character counts for welcome, abandoned cart, browse abandonment, post-purchase, win-back, promotional, transactional, re-engagement, replenishment, VIP - references/platforms.md: platform deep-dives across Klaviyo SMS, Postscript, Attentive, Twilio, Plivo, AudienceTap, Brevo, SimpleTexting, Customer.io - evals/evals.json: 6 evals covering getting started, abandoned cart, TCPA compliance, opt-out diagnosis, A2P throughput, emoji segment cost New integration docs: - tools/integrations/twilio.md - tools/integrations/postscript.md - tools/integrations/attentive.md - tools/integrations/plivo.md - tools/integrations/audiencetap.md Registry + marketplace wiring: - tools/REGISTRY.md: 5 new entries + new SMS / Messaging category section - .claude-plugin/marketplace.json: bumped to 2.1.0, SMS added to plugin description - VERSIONS.md: sms 1.0.0 + 2.1.0 changelog entry - README.md: skill table re-sorted via sync-skills.js, sms added to ASCII flow All 41 skills pass validation. sync-skills.js is idempotent on current state. Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-21 16:44:47 -07:00
parent 908500123b
commit d36433703b
14 changed files with 1966 additions and 2 deletions
@@ -54,6 +54,11 @@ Quick reference for AI agents to discover tool capabilities and integration meth
 | postmark | Email | ✓ | - | [✓](clis/postmark.js) | ✓ | [postmark.md](integrations/postmark.md) |
 | brevo | Email/SMS | ✓ | - | [✓](clis/brevo.js) | ✓ | [brevo.md](integrations/brevo.md) |
 | activecampaign | Email/CRM | ✓ | - | [✓](clis/activecampaign.js) | ✓ | [activecampaign.md](integrations/activecampaign.md) |
+| twilio | SMS/Voice | ✓ | - | ✓ | ✓ | [twilio.md](integrations/twilio.md) |
+| plivo | SMS/Voice | ✓ | - | - | ✓ | [plivo.md](integrations/plivo.md) |
+| postscript | SMS | ✓ | - | - | - | [postscript.md](integrations/postscript.md) |
+| attentive | SMS | ✓ | - | - | - | [attentive.md](integrations/attentive.md) |
+| audiencetap | SMS/Email | ✓ | - | - | - | [audiencetap.md](integrations/audiencetap.md) |
 | hunter | Email Outreach | ✓ | - | [✓](clis/hunter.js) | - | [hunter.md](integrations/hunter.md) |
 | snov | Email Outreach | ✓ | - | [✓](clis/snov.js) | - | [snov.md](integrations/snov.md) |
 | lemlist | Email Outreach | ✓ | - | [✓](clis/lemlist.js) | - | [lemlist.md](integrations/lemlist.md) |
@@ -189,6 +194,23 @@ Email marketing, transactional email, and automation platforms.

 **Agent recommendation**: Resend for transactional (dev-friendly). Postmark for deliverability. Customer.io for advanced automation. Kit for creators. Beehiiv for newsletters. Klaviyo for e-commerce email/SMS. ActiveCampaign for email + CRM combo.

+### SMS / Messaging
+
+SMS and MMS marketing platforms and programmable messaging APIs.
+
+| Tool | Best For | MCP Available |
+|------|----------|:-------------:|
+| **klaviyo** | DTC ecom already on Klaviyo email | - |
+| **postscript** | Shopify DTC, SMS-first depth | - |
+| **attentive** | Mid-market+ DTC, full-service | - |
+| **twilio** | Custom API builds, transactional, dev-first | - |
+| **plivo** | Twilio alternative, lower per-send cost | - |
+| **audiencetap** | DTC with AI-forward creative + on-pack QR opt-in | - |
+| **brevo** | EU SMB email + SMS combo | - |
+| **customer-io** | Behavior-based SMS automation | - |
+
+**Agent recommendation**: Klaviyo SMS for ecom already on Klaviyo email. Postscript for Shopify-first depth. Attentive for mid-market+ wanting concierge support. Twilio (or Plivo for lower cost) for custom builds and transactional/auth. AudienceTap when AI creative or on-pack QR opt-in matters.
+
 ### Advertising

 Paid advertising platforms and campaign management.
@@ -0,0 +1,152 @@
+# Attentive
+
+Full-service SMS marketing platform for mid-market and enterprise direct-to-consumer brands. Combines tooling with dedicated success teams.
+
+## Capabilities
+
+| Integration | Available | Notes |
+|-------------|-----------|-------|
+| API | ✓ | REST API |
+| MCP | - | Not available |
+| CLI | - | None |
+| SDK | - | Use API directly |
+
+## Authentication
+
+- **Type**: OAuth 2.0 or API Key (depending on integration type)
+- **Header**: `Authorization: Bearer {access_token}`
+- **Get credentials**: Account-level provisioning through Attentive integrations team
+- **Note**: API access requires partnership or eligible plan
+
+## Common Agent Operations
+
+### Subscribe a user
+
+```bash
+POST https://api.attentivemobile.com/v1/subscriptions
+
+{
+  "user": {
+    "phone": "+15551234567",
+    "email": "user@example.com"
+  },
+  "signUpSourceId": "...",
+  "subscriptionType": "MARKETING"
+}
+```
+
+Sign-up source ID determines opt-in attribution and compliance disclosure shown.
+
+### Unsubscribe
+
+```bash
+POST https://api.attentivemobile.com/v1/subscriptions/unsubscribe
+
+{
+  "user": { "phone": "+15551234567" },
+  "subscriptionType": "MARKETING"
+}
+```
+
+### Custom event tracking
+
+```bash
+POST https://api.attentivemobile.com/v1/events/custom
+
+{
+  "user": { "phone": "+15551234567" },
+  "type": "abandoned_cart",
+  "properties": {
+    "cart_value": 89.99,
+    "items": ["Product A"]
+  }
+}
+```
+
+### E-commerce events (purchase, add-to-cart, product view)
+
+```bash
+POST https://api.attentivemobile.com/v1/events/ecommerce/purchase
+
+{
+  "user": { "phone": "+15551234567" },
+  "items": [{
+    "productId": "SKU-123",
+    "name": "Product A",
+    "price": { "value": 4999, "currency": "USD" },
+    "quantity": 1
+  }],
+  "occurredAt": "2026-05-15T10:00:00Z"
+}
+```
+
+Similar endpoints for `/add_to_cart`, `/product_view`, `/checkout`.
+
+### Send transactional message
+
+```bash
+POST https://api.attentivemobile.com/v1/messages/transactional
+
+{
+  "user": { "phone": "+15551234567" },
+  "messageBody": "Your order #1234 shipped. Track: https://...",
+  "type": "ORDER_SHIPPING"
+}
+```
+
+### List campaigns
+
+```bash
+GET https://api.attentivemobile.com/v1/campaigns
+```
+
+### Webhooks
+
+Subscribe to: `subscriber.created`, `subscriber.unsubscribed`, `message.sent`, `message.delivered`, `message.failed`, `conversion.attributed`.
+
+## API Pattern
+
+REST + JSON. Bearer auth. Webhook signature verification via HMAC-SHA256.
+
+## Key Features
+
+- Concierge sales (live agents responding via SMS)
+- Identity resolution (matching anonymous site visitors to phone numbers for retargeting)
+- Strong analytics + attribution (multi-touch, conversion path)
+- AI Journey AI / Pro AI (AI-generated send timing and copy)
+- Custom Audience Manager (advanced segmentation)
+- A/B testing built into campaign builder
+- Two-way SMS at scale
+- A2P 10DLC fully managed
+- Short code provisioning included on most plans
+- Dedicated CSM, copy support, strategy consults
+
+## Pricing
+
+- Custom contracts; typically $1K–$10K+/mo platform fee + per-send fees
+- Annual contracts standard
+- Pricing rarely makes sense for <50K active SMS subscribers
+- Negotiable based on volume and tier
+
+## When to Use
+
+- Mid-market+ DTC brand (50K+ active SMS subscribers, $5M+/yr revenue)
+- Want dedicated CSM and copy support, not just tooling
+- Need concierge two-way SMS at scale
+- Multi-channel ecom team that wants single-pane SMS-first platform
+- Want short code included rather than separately leased
+- Identity resolution / cross-device matching matters
+
+## When NOT to Use
+
+- Smaller brands — too expensive, overkill
+- Already on Klaviyo and SMS is secondary — Klaviyo SMS is simpler
+- Shopify-only and want depth — Postscript is more Shopify-native
+- Custom platform / B2B SaaS — Twilio
+
+## Relevant Skills
+
+- sms
+- emails (run alongside)
+- churn-prevention
+- customer-research (identity resolution data)
@@ -0,0 +1,125 @@
+# AudienceTap
+
+SMS and email marketing platform built for direct-to-consumer brands. Newer entrant positioning as a more flexible, AI-forward alternative to Klaviyo / Postscript / Attentive with emphasis on creative automation and on-pack QR opt-in.
+
+## Capabilities
+
+| Integration | Available | Notes |
+|-------------|-----------|-------|
+| API | ✓ | REST API (confirm with vendor; access tied to plan tier) |
+| MCP | - | Not available |
+| CLI | - | None |
+| SDK | - | Use API directly |
+
+> Verify current API surface and capabilities at https://audiencetap.com before building against this guide — newer platform, surface evolves quickly.
+
+## Authentication
+
+- **Type**: API Key (Bearer)
+- **Header**: `Authorization: Bearer {api_key}`
+- **Get key**: AudienceTap dashboard → Settings → API
+- **Note**: API access generally requires Growth or Pro tier
+
+## Common Agent Operations
+
+### Subscribe a user
+
+```bash
+POST https://api.audiencetap.com/v1/subscribers
+
+{
+  "phone_number": "+15551234567",
+  "email": "user@example.com",
+  "first_name": "Jane",
+  "opt_in_source": "checkout",
+  "list_id": "..."
+}
+```
+
+### Unsubscribe
+
+```bash
+POST https://api.audiencetap.com/v1/subscribers/unsubscribe
+
+{
+  "phone_number": "+15551234567",
+  "channel": "sms"
+}
+```
+
+### Track event
+
+```bash
+POST https://api.audiencetap.com/v1/events
+
+{
+  "subscriber": { "phone_number": "+15551234567" },
+  "event_name": "abandoned_cart",
+  "properties": {
+    "cart_value": 89.99,
+    "items": ["Product A"]
+  }
+}
+```
+
+### Send transactional message
+
+```bash
+POST https://api.audiencetap.com/v1/messages/transactional
+
+{
+  "phone_number": "+15551234567",
+  "body": "Your order #1234 shipped. Track: https://...",
+  "category": "shipping"
+}
+```
+
+### List flows / automations
+
+```bash
+GET https://api.audiencetap.com/v1/flows
+```
+
+### Webhooks
+
+Subscribe to: subscriber events, message delivery events, conversion attribution. Configured in dashboard.
+
+## API Pattern
+
+REST + JSON. Bearer auth. Pagination conventions vary by endpoint — confirm in current docs.
+
+## Key Features
+
+- SMS + email on one platform (positioned similarly to Klaviyo's combined product)
+- AI creative generation (subject lines, SMS copy, image variants)
+- On-pack QR code opt-in (insert-card based opt-in for ecom shipments)
+- Shopify, BigCommerce, and headless commerce integrations
+- A2P 10DLC handled in-platform
+- Automation builder for cart, post-purchase, win-back, etc.
+- Identity resolution (matching anonymous visitors to known subscribers)
+
+## Pricing
+
+- Plans typically tiered by subscriber count + send volume
+- Per-send pricing comparable to other DTC SMS platforms (~$0.015 SMS, ~$0.04 MMS)
+- Confirm current pricing at https://audiencetap.com — newer platform with evolving plans
+
+## When to Use
+
+- Mid-market DTC brand willing to try a newer platform for better AI tooling or pricing leverage
+- Brand wanting on-pack QR opt-in as a primary acquisition channel (printed insert cards driving SMS opt-in)
+- Want SMS + email under one roof with stronger AI features than incumbents currently offer
+- Evaluating alternatives during a contract negotiation with Klaviyo / Postscript / Attentive
+
+## When NOT to Use
+
+- Need a fully battle-tested platform with deep ecosystem — incumbents have more integrations and case studies
+- Compliance tooling at enterprise scale — verify A2P / TCPA depth before committing for large lists
+- B2B SaaS, transactional, or developer-first use — Twilio or Plivo
+
+## Relevant Skills
+
+- sms
+- emails
+- referrals (on-pack QR opt-in is a referral-adjacent acquisition channel)
+- directory-submissions (on-pack insert cards as an offline channel)
@@ -0,0 +1,140 @@
+# Plivo
+
+Cloud communications API platform — SMS, MMS, voice, WhatsApp. Direct Twilio competitor with similar pricing and developer-first positioning.
+
+## Capabilities
+
+| Integration | Available | Notes |
+|-------------|-----------|-------|
+| API | ✓ | REST API |
+| MCP | - | Not available |
+| CLI | - | None official |
+| SDK | ✓ | Node, Python, Ruby, PHP, Java, Go, .NET |
+
+## Authentication
+
+- **Type**: Basic auth with Auth ID + Auth Token
+- **Header**: `Authorization: Basic base64(AuthID:AuthToken)`
+- **Get credentials**: https://console.plivo.com → Account → Account Settings
+- **Note**: Subaccounts available for isolating environments or customers
+
+## Common Agent Operations
+
+### Send SMS
+
+```bash
+POST https://api.plivo.com/v1/Account/{AuthID}/Message/
+
+{
+  "src": "+15559876543",
+  "dst": "+15551234567",
+  "text": "Hello from Plivo"
+}
+```
+
+### Send MMS
+
+```bash
+POST https://api.plivo.com/v1/Account/{AuthID}/Message/
+
+{
+  "src": "+15559876543",
+  "dst": "+15551234567",
+  "text": "Check this out",
+  "type": "mms",
+  "media_urls": ["https://example.com/image.jpg"]
+}
+```
+
+### Bulk send (powerpack)
+
+Use Plivo's Powerpack feature to send from a pool of numbers with sticky sender + automatic A2P registration. Configured in console; messages then sent with `powerpack_uuid` instead of `src`.
+
+```bash
+POST https://api.plivo.com/v1/Account/{AuthID}/Message/
+
+{
+  "powerpack_uuid": "...",
+  "dst": "+15551234567",
+  "text": "Hello"
+}
+```
+
+### Get message details
+
+```bash
+GET https://api.plivo.com/v1/Account/{AuthID}/Message/{MessageUUID}/
+```
+
+### List messages
+
+```bash
+GET https://api.plivo.com/v1/Account/{AuthID}/Message/?limit=20&offset=0
+```
+
+### Rent a phone number
+
+```bash
+# Search available
+GET https://api.plivo.com/v1/Account/{AuthID}/PhoneNumber/?country_iso=US&type=local
+
+# Rent
+POST https://api.plivo.com/v1/Account/{AuthID}/PhoneNumber/{NumberID}/
+```
+
+### Configure inbound message webhook on an Application
+
+```bash
+POST https://api.plivo.com/v1/Account/{AuthID}/Application/
+
+{
+  "app_name": "SMS Receiver",
+  "message_url": "https://your-app.com/sms-webhook",
+  "message_method": "POST"
+}
+```
+
+Then assign the application to the phone number.
+
+### A2P 10DLC registration (US)
+
+Configured through console UI under Compliance. Programmatic registration available for high-volume customers via dedicated API endpoints (request access).
+
+## API Pattern
+
+REST + JSON. Pagination via `limit` + `offset`. Webhook callbacks for inbound messages and delivery status (configured per-application).
+
+## Pricing
+
+- US 10DLC SMS: $0.0055/msg (typically lower than Twilio)
+- US toll-free SMS: $0.0055/msg
+- US short code SMS: similar + monthly lease
+- MMS: ~$0.02
+- Carrier surcharges layered on top
+- Phone number rental: ~$0.80/mo local, ~$1/mo toll-free
+
+Plivo typically prices 5–20% under Twilio at the per-send level. Less of an ecosystem advantage but real cost savings at high volume.
+
+## Rate Limits
+
+- Default: 1 msg/sec
+- Powerpacks scale throughput based on number pool size and A2P trust
+- Short codes: 100+ msg/sec
+
+## When to Use
+
+- Custom SMS build, want a Twilio-like API with lower cost
+- High-volume sending where the per-message delta matters
+- Want bulk sending with sticky sender via Powerpack
+- B2B SaaS embedding SMS or transactional/auth at scale
+
+## When NOT to Use
+
+- DTC ecom marketing flows — Klaviyo, Postscript, Attentive
+- Ecosystem matters more than price — Twilio's broader product surface (Voice, Studio, SendGrid, Segment, etc.) wins
+- Need mature WhatsApp Business — Twilio has deeper WhatsApp tooling
+
+## Relevant Skills
+
+- sms
+- onboarding (post-signup notifications)
@@ -0,0 +1,126 @@
+# Postscript
+
+SMS marketing platform built for Shopify direct-to-consumer brands. Deepest Shopify integration of any SMS platform.
+
+## Capabilities
+
+| Integration | Available | Notes |
+|-------------|-----------|-------|
+| API | ✓ | REST API |
+| MCP | - | Not available |
+| CLI | - | None |
+| SDK | - | Use API directly |
+
+## Authentication
+
+- **Type**: API Key
+- **Header**: `Authorization: Bearer {api_key}` or `X-Postscript-Api-Key: {api_key}`
+- **Get key**: Postscript dashboard → Settings → API
+- **Note**: Keys are scoped per shop
+
+## Common Agent Operations
+
+### Search subscribers
+
+```bash
+GET https://api.postscript.io/api/v2/subscribers?phone_number=%2B15551234567
+```
+
+### Create subscriber (opt-in)
+
+```bash
+POST https://api.postscript.io/api/v2/subscribers
+
+{
+  "phone_number": "+15551234567",
+  "email": "user@example.com",
+  "first_name": "Jane",
+  "subscribed_at": "2026-05-15T10:00:00Z",
+  "opt_in_source": "checkout_keyword"
+}
+```
+
+Must include valid opt-in metadata for TCPA compliance.
+
+### Unsubscribe
+
+```bash
+DELETE https://api.postscript.io/api/v2/subscribers/{subscriberId}/subscription
+```
+
+### List keywords (e.g., JOIN, SAVE)
+
+```bash
+GET https://api.postscript.io/api/v2/keywords
+```
+
+### Send transactional message
+
+```bash
+POST https://api.postscript.io/api/v2/transactional/sms
+
+{
+  "phone_number": "+15551234567",
+  "message": "Your order #1234 shipped. Track at https://..."
+}
+```
+
+Transactional requires separate enablement; counts under transactional consent.
+
+### List campaigns
+
+```bash
+GET https://api.postscript.io/api/v2/campaigns
+```
+
+### List automations (flows)
+
+```bash
+GET https://api.postscript.io/api/v2/automations
+```
+
+### Webhooks
+
+Subscribe to events: `subscriber.created`, `subscriber.unsubscribed`, `message.delivered`, `message.failed`, `conversion.attributed`.
+
+## API Pattern
+
+REST + JSON. Standard `Bearer` auth. Pagination via `cursor` and `limit` (max 100).
+
+## Key Features
+
+- Native Shopify integration: purchases, abandoned carts, browse, product catalog auto-sync
+- Strong abandoned cart and browse abandonment automation builders
+- AI Reply (auto-reply trained on brand voice)
+- Conversational SMS / live agent for two-way
+- Opt-in tools: popups, keyword opt-in, checkout opt-in
+- A2P 10DLC managed in-platform
+- Reporting: revenue, click-through, conversion attribution, opt-out rate
+
+## Pricing
+
+- Plans: Starter (free, 1K msgs/mo), Growth ($100+/mo), Professional, Enterprise
+- Per-send pricing on top: ~$0.015 SMS, ~$0.04 MMS
+- Annual contracts standard at Growth+
+- Pricing scales meaningfully past 50K subscribers
+
+## When to Use
+
+- Shopify DTC brand wanting SMS-specific tooling (vs combined email/SMS)
+- Need deep abandoned cart, browse abandonment, post-purchase automation out of the box
+- Want managed A2P 10DLC + compliance tools
+- Mid-size DTC brand (10K–500K SMS subscribers)
+
+## When NOT to Use
+
+- Non-Shopify ecom — integration is shallow
+- Already on Klaviyo for email and SMS is secondary — Klaviyo SMS is simpler
+- Mid-market/enterprise needing concierge support — Attentive
+- Custom platform or B2B SaaS — Twilio
+
+## Relevant Skills
+
+- sms
+- emails (run alongside via Klaviyo or similar)
+- churn-prevention (win-back flows)
+- onboarding (post-purchase activation)
@@ -0,0 +1,152 @@
+# Twilio
+
+Programmable communications platform: SMS, MMS, WhatsApp, voice, email (via SendGrid). The default low-level API for custom SMS builds, transactional messaging, and B2B SaaS embedding SMS into products.
+
+## Capabilities
+
+| Integration | Available | Notes |
+|-------------|-----------|-------|
+| API | ✓ | REST API, well-documented, mature |
+| MCP | - | Not available natively (community wrappers exist) |
+| CLI | ✓ | Official `twilio` CLI |
+| SDK | ✓ | Node, Python, Ruby, PHP, Java, Go, C#, .NET |
+
+## Authentication
+
+- **Type**: Basic auth with Account SID + Auth Token (or API Key SID + Secret)
+- **Header**: `Authorization: Basic base64(AccountSID:AuthToken)`
+- **Get credentials**: https://console.twilio.com → Account Info
+- **Recommendation**: Use API Keys (revocable, scoped) for production rather than the master Auth Token
+
+## Common Agent Operations
+
+### Send SMS
+
+```bash
+POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages.json
+
+To=+15551234567
+From=+15559876543
+Body=Hello from Twilio
+```
+
+### Send MMS
+
+```bash
+POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages.json
+
+To=+15551234567
+From=+15559876543
+Body=Check this out
+MediaUrl=https://example.com/image.jpg
+```
+
+### List messages
+
+```bash
+GET https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages.json?PageSize=50
+```
+
+### Get message status
+
+```bash
+GET https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/Messages/{MessageSid}.json
+```
+
+Status values: `queued`, `sending`, `sent`, `delivered`, `undelivered`, `failed`.
+
+### List phone numbers
+
+```bash
+GET https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/IncomingPhoneNumbers.json
+```
+
+### Buy a phone number
+
+```bash
+POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/IncomingPhoneNumbers.json
+
+PhoneNumber=+15559876543
+```
+
+### Configure webhook for inbound messages
+
+```bash
+POST https://api.twilio.com/2010-04-01/Accounts/{AccountSid}/IncomingPhoneNumbers/{Sid}.json
+
+SmsUrl=https://your-app.com/sms-webhook
+SmsMethod=POST
+```
+
+Inbound SMS POSTs to the webhook with: `From`, `To`, `Body`, `MessageSid`, `NumMedia`, etc.
+
+### A2P 10DLC registration (US)
+
+```bash
+# Create brand
+POST https://messaging.twilio.com/v1/a2p/BrandRegistrations
+
+CustomerProfileBundleSid=...
+A2PProfileBundleSid=...
+
+# Create campaign
+POST https://messaging.twilio.com/v1/Services/{ServiceSid}/Compliance/Usa2p
+
+BrandRegistrationSid=...
+Description=...
+MessageSamples[]=Sample text 1
+MessageFlow=Opt-in flow description
+UseCase=MARKETING
+```
+
+Most workflows are clearer in the Console UI. Programmatic registration is for high-scale platforms managing many brands.
+
+## API Pattern
+
+REST + form-encoded request bodies (not JSON for most endpoints). Resources nested under Account: `/Accounts/{AccountSid}/...`. Pagination via `Page`, `PageSize`, `NextPageUri`.
+
+## Key Concepts
+
+- **Messaging Service**: virtual sender container; load-balances across multiple numbers, handles A2P registration grouping
+- **Sticky Sender**: same recipient always receives from the same number within a service
+- **Geo-Match**: route to a number matching the recipient's country/region
+- **Status Callback**: webhook fired on every delivery state change
+- **Carrier Lookup**: pre-send check for line type (mobile, landline, VoIP) — costs ~$0.005
+
+## Pricing
+
+- US 10DLC SMS: $0.0079/msg
+- US toll-free SMS: $0.0079/msg
+- US short code SMS: $0.0079/msg + $1,000/mo lease
+- MMS: ~$0.02
+- Carrier surcharges (~$0.005 US 10DLC)
+- A2P 10DLC: ~$15 brand + $10/mo per campaign
+- Phone number rental: $1.15/mo (10DLC) to $2/mo (toll-free)
+
+## Rate Limits
+
+- Default: 1 msg/sec on long codes (10DLC trust score raises this to 4–100+)
+- Short code: 100+ msg/sec
+- Messaging Services throttle automatically
+- Carrier filtering applies above contracted throughput
+
+## When to Use
+
+- Building custom SMS flows into a product (B2B SaaS, mobile apps)
+- Transactional and auth SMS (OTPs, alerts, notifications)
+- Multi-channel orchestration (SMS + voice + WhatsApp)
+- High-volume programmable messaging
+- When you need full control and minimal abstraction
+- Backing store for Customer.io / Segment / other orchestration layers
+
+## When NOT to Use
+
+- DTC ecom marketing flows — use Klaviyo, Postscript, or Attentive (better tooling for cart recovery, segments, A/B tests)
+- If you don't want to handle compliance plumbing — Twilio gives you primitives, not policy
+- Marketing UI for non-technical users — there isn't one
+
+## Relevant Skills
+
+- sms
+- emails (transactional sister product via SendGrid)
+- onboarding (post-signup SMS milestones)