twilio-numbers-senders

What this skill does

## Overview

Choosing the right number type and sender is the **first decision** in any Twilio project. Each number type comes with its own compliance/verification program, throughput limits, and capabilities. Developers who skip this step buy numbers first, build their app, then discover they chose the wrong type.

**Lifecycle:** Choose numbers/senders (this skill) → Register them (`twilio-compliance-onboarding`) → Follow traffic rules (`twilio-compliance-traffic`)

---

## US Number Types — Comparison

| | **Local (10DLC)** | **Toll-Free** (800/888/877) | **Short Code** (5-6 digits) |
|---|---|---|---|
| **SMS** | Yes | Yes | Yes |
| **MMS** | Yes | Yes | Yes |
| **Voice** | Yes | Yes | No |
| **Two-way** | Yes | Yes | Yes |
| **Throughput** | ~1-75+ SMS/sec (varies by trust score) | ~3 SMS/sec | 10-100 SMS/sec |
| **Compliance program** | **A2P 10DLC** (brand + campaign) | **Toll-Free Verification** | **Pre-approved at purchase** (carrier review) |
| **Approval timeline** | 10-15 business days | 3-5 business days | 8-12 weeks provisioning |
| **Best for** | Transactional, marketing, support | Notifications, support, verification | High-volume marketing, 2FA |
| **Cost** | Lowest | Medium | Highest (setup + monthly + per-msg) |

Source: [US/Canada SMS comparison](https://help.twilio.com/articles/360038173654-Comparison-of-SMS-messaging-in-the-US-and-Canada-for-long-codes-short-codes-and-toll-free-phone-numbers)

### Compliance Programs Per Number Type

Every US number type requires its own verification before traffic flows:

- **Local 10DLC → A2P 10DLC registration:** Brand registration (EIN, business identity) + Campaign registration (use case, sample messages, opt-in flow). Trust Score determines throughput. Sole Proprietors: ~1 SMS/sec, 1 campaign. Standard: ~15+ SMS/sec, scales with secondary vetting. [A2P overview](https://www.twilio.com/docs/messaging/compliance/a2p-10dlc) | [Quickstart](https://www.twilio.com/docs/messaging/compliance/a2p-10dlc/quickstart)

- **Toll-Free → Toll-Free Verification (TFV):** Business name, website, use case description, sample messages, opt-in type. Unverified toll-free numbers **cannot send SMS to US/Canada**. [Console onboarding](https://www.twilio.com/docs/messaging/compliance/toll-free/console-onboarding) | [Requirements](https://help.twilio.com/articles/5377174717595-Toll-Free-Message-Verification-for-US-Canada)

- **Short Code → Carrier review at purchase:** Application reviewed during 8-12 week provisioning. Available in 14 countries: US, Canada, UK, Germany, France, India, Brazil, Mexico, Argentina, Colombia, Dominican Republic, New Zealand, Spain, Sweden. [Short code guidelines by country](https://www.twilio.com/en-us/guidelines/short-code) | [What is a short code?](https://help.twilio.com/articles/223182068-What-is-a-Messaging-Short-Code-)

- **Twilio Verify → Exempt.** No registration needed — Verify handles compliance automatically.

See `twilio-compliance-onboarding` for full registration details and gotchas.

---

## How to Choose (US)

- **Need voice + SMS from same number?** → Local (10DLC) or toll-free. Short codes are SMS-only.
- **Marketing at scale (>15 SMS/sec)?** → Short code (highest throughput) or 10DLC with secondary vetting + Messaging Service number pool
- **Fastest time to send?** → Toll-free (3-5 day verification) or Twilio Verify (immediate, no registration)
- **Customer support with local presence?** → Local number in customer's area code
- **Transactional notifications?** → Toll-free (simpler registration) or 10DLC
- **Verification OTPs?** → Twilio Verify (exempt from A2P, built-in Fraud Guard)
- **Budget-constrained?** → 10DLC (lowest cost) — but plan for 10-15 day registration

---

## Non-Phone Senders

### Alphanumeric Sender IDs

A branded name (up to 11 characters) displayed instead of a phone number. **One-way only — recipients cannot reply.**

- **Not supported in the US or Canada**
- Supported in 100+ countries; some require pre-registration with documentation
- Some carriers impose minimum length — short IDs may display as "unknown"
- Add to Messaging Services for automatic sender selection by destination country

**Docs:** [Alpha Sender in Messaging Services](https://www.twilio.com/docs/messaging/services/alphanumeric-sender-ids-in-messaging-services) | [International support by country](https://help.twilio.com/articles/223133767-International-support-for-Alphanumeric-Sender-ID) | [How to register](https://help.twilio.com/articles/20153208099611-How-to-Register-an-Alphanumeric-Sender-ID)

### WhatsApp Business Senders

A phone number registered with Meta's WhatsApp Business Platform via Twilio.

- Requires WABA (WhatsApp Business Account) + sender approval
- Outbound requires pre-approved Message Templates (outside 24-hour service window)
- Direct customers: self-service Console signup or Senders API
- ISVs: Meta Tech Provider Program for customer onboarding

**Docs:** [WhatsApp hub](https://www.twilio.com/docs/whatsapp) | [Getting started](https://help.twilio.com/articles/360007721954-Getting-Started-with-Twilio-for-WhatsApp) | [Self sign-up](https://www.twilio.com/docs/whatsapp/self-sign-up)

### RCS Agents

Branded sender with logo, rich cards, carousels, and suggested actions. Falls back to SMS automatically.

- Requires carrier-level approval per country
- Testing phase: RCS only delivers to added test devices; others get SMS fallback
- Each RCS sender can only belong to ONE Messaging Service

**Docs:** [RCS onboarding](https://www.twilio.com/docs/rcs/onboarding) | [RCS compliance guide](https://help.twilio.com/articles/49174994355355-RCS-Compliance-Onboarding-Guide) | [Regional availability](https://www.twilio.com/docs/rcs/regional)

---

## Voice Trust: Number Reputation Programs

If making outbound voice calls, these programs improve answer rates:

| Program | What it does | Carriers | Prerequisites |
|---------|-------------|----------|---------------|
| **STIR/SHAKEN** | Level A attestation = trusted caller ID | US and Canada | Trust Hub Business Profile + EIN |
| **Voice Integrity** | Remediates spam/scam labels | T-Mobile, AT&T, Verizon (coming) | Approved Business Profile + US address |
| **Branded Calling** | Shows name + logo on caller ID | T-Mobile, Verizon (Public Beta) | STIR/SHAKEN + Trust Hub profile |
| **CNAM** | Displays business name on caller ID | US long codes only (not toll-free) | EIN or DUNS number |

**Priority order:** STIR/SHAKEN first (required for Level A attestation) → Voice Integrity (spam label remediation) → Branded Calling (visual caller ID, mobile only) → CNAM (simplest, lowest impact, landlines by default).

**Docs:** [STIR/SHAKEN overview](https://www.twilio.com/docs/voice/trusted-calling-with-shakenstir) | [Voice Integrity overview](https://www.twilio.com/docs/voice/spam-monitoring-with-voiceintegrity) | [Branded Calling overview](https://www.twilio.com/docs/voice/branded-calling) | [CNAM overview](https://www.twilio.com/docs/voice/brand-your-calls-using-cnam)

### Branded Calling: Prerequisites & Display Standards

The call trust stack is layered — each product builds on the one below:

```
Layer 4: Enhanced Branded Calling  (name + logo + call reason)
         ↑ requires
Layer 3: Basic Branded Calling     (business name display)
         ↑ requires
Layer 2: Voice Integrity           (spam label remediation)
         ↑ requires
Layer 1: SHAKEN/STIR               (attestation — auto-applied with approved profile)
         ↑ requires
Layer 0: Primary Customer Profile  (Trust Hub business identity)
```

**Prerequisites for Basic Branded Calling:**
1. Approved Primary Customer Profile in Trust Hub (EIN, business name, address, authorized rep) — 1-3 business days
2. SHAKEN/STIR — automatic once profile is approved
3. Signed Letter of Authorization (LOA) for the phone numbers
4. Basic Branded Calling trust product submitted + approved — 2-4 weeks

**Additional prerequisites for Enhanced Branded Calling:**
5. Approved Voice Integr