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Twilio

First met in aicp-c3-basecamp-06 · Messaging & telephony

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Phone numbers and SIP trunking — the plumbing that connects a voice agent to the actual telephone network.

Pick this when

You need real numbers, especially outside the US, and you don't want to pay a voice platform's resale markup.

What makes it different

Numbers in effectively any country, where voice platforms typically resell US/CA only

SIP trunking connects those numbers to the agent platform

Clients host their own account, so the phone bill and the liability stay theirs

What it does

Sells phone numbers by country

Provides SIP trunk configuration to route calls into a voice platform

What it does not do

Common wrong expectations

Doesn't build the agent — it's the line, not the voice on it

Doesn't configure itself; SIP trunk setup is a real step in the build

Where it sits in a stack

Underneath the voice-agent platform, owned by whoever should be paying for the calls.

Shelf

Messaging & telephony

Our status · not-using

No telephony.

For your projects

None.

Freshness

current

Related tools

complementsRetell AI

retell-ai: numbers and SIP trunk feed Retell; cheaper than its resold numbers

Every moment the course touched it (7)

SessionCoverageMomentWhat happened
Basecamp 6: Voice Agentsexplained0:51:37Preferred telephony provider: buy any country's numbers, SIP trunk setup, cheaper than Retell's resold numbers; clients host their own accounts
Day 6: Voice Agents That Talk Like Humans — the 5-Step Pipeline, Retell Settings That Matter, the 5-Section Prompt, cal.com Booking, and Call LoggingexplainedNumbers + elastic SIP trunk
Founder Stack Ep01: How an AI Voice Agency Actually Makes Money — Matthew Cohn on Content as the Only Free Channel, Value-Based Pricing, the Three-Problem Rule, and SOPs Before HiringmentionedDefault telephony for UK, US and Australia clients.
Session 29: Build Always-On Assistants — Autonomy Is Designed, Not Switched On (OpenClaw on a VPS, Hermes on the Desktop)mentionedRequired for the agent to place an actual phone call; he does not have an account, so the call demo is partial.
Session 30: C3 Town Hall — Four Cohort Products Under the Knife, Outcome Selling, and the Rest of the ProgrammementionedPhone number provisioning for the receptionist; a per-client cost she names as the reason she has not launched her other 15 niches.
Day 14: Graduation — Skills, Systems, Dollars: the Niche Framework, the First-Dollar Roadmap, Pricing, Moats, and What Happens NextmentionedTelephony in the support stack
Bonus Session (Day 3): No-Code Automation in Make.com - Form to Sheet to Email, the 7-Step Process, and a Daily AI Image-and-Caption Poster for Instagram and LinkedInmentionedSMS example

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