twilio-numbers-senders

twilio-numbers-senders is a skill for Claude Code, Codex from twilio/ai. It costs 73 tokens per session (3,311 once invoked), scanned A, original, MIT.

Guidance for choosing a Twilio phone number or messaging sender before building a communications application. It covers local, toll-free, short-code, mobile, alphanumeric, WhatsApp, and RCS senders, including availability and registration requirements.

In plain words
What is it for?
Use it to select a sender for SMS, MMS, voice, WhatsApp, or RCS, compare number types, and understand the registration or verification process required for each choice.
Why use it?
Different sender types support different channels, speeds, countries, and compliance programs. Choosing the wrong one can force changes to the application and delay approval.

Skill for Claude CodeCodex ✓ vendor

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also agents/openai.yaml present.

Part of the ai plugin — 57 skills shipped together

Good fit Use it to select a sender for SMS, MMS, voice, WhatsApp, or RCS, compare number types, and understand the registration or verification process required for each choice.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/twilio/ai/twilio-numbers-senders
View source ↗ twilio/ai
About the project

Twilio for AI provides coding agents with skills and an MCP server for using Twilio services and documentation. The MCP server searches Twilio documentation and API specifications and retrieves full schemas for selected operations, while the skills supply procedural guidance to agents. Its catalogue add-ons are intended for Claude Code, Cursor, Codex, and other tools that support the Agent Skills standard.

twilio/ai · 32 stars · on GitHub

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add twilio/ai --skill twilio-numbers-senders
Clone the repo
git clone --depth 1 https://github.com/twilio/ai

Made for: Claude Code, Codex.

Or install ai, the plugin that ships this one along with the rest of its 57 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for twilio-numbers-senders

README.md
[![agentmods](https://agentmods.dev/badge/skills/twilio/ai/twilio-numbers-senders/github.svg)](https://agentmods.dev/skills/twilio/ai/twilio-numbers-senders)
Your own site
<a href="https://agentmods.dev/skills/twilio/ai/twilio-numbers-senders"><img src="https://agentmods.dev/badge/skills/twilio/ai/twilio-numbers-senders/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for twilio-numbers-senders

Your own site · 80×15
<a href="https://agentmods.dev/skills/twilio/ai/twilio-numbers-senders"><img src="https://agentmods.dev/badge/skills/twilio/ai/twilio-numbers-senders.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 73 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,311 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Excessive Agency · line 170
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00073 $0.03311
Opus 5 $0.00036 $0.01656
Sonnet 5 $0.00015 $0.00662
Haiku 4.5 $0.00007 $0.00331

Measured 12d ago against content hash de7b4c12d3e6, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

twilio-numbers-senders scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/twilio/twilio-numbers-senders/SKILL.md · 223 lines

How it starts

The opening of the file, as written. The whole thing — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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

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 | Quickstart

Read the full file on GitHub · 223 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 12d ago First seen · 223 lines · 73 tokens per session scan A de7b4c12d3e6

Subscribe to this mod's changes

twilio-numbers-senders is a skill published in the GitHub repository twilio/ai (32 stars, last pushed 28d ago), licensed MIT. It adds 73 tokens to every session and 3,311 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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