Agentline
Give Your AI Agent a Real Phone Number — No Telecom Degree Required
AgentLine is the missing piece between your AI agent and the phone network. If your agent can process text, AgentLine lets it make and receive phone calls. That's it. That's the whole pitch.
But what that actually unlocks is worth understanding.
The Problem AgentLine Solves
Most AI agents today are stuck in text-only mode. They can write code, answer questions, generate content — but they can't pick up a phone when a customer calls. That gap limits what your agent can do in ways that aren't obvious until you hit it.
You're a SaaS founder. A customer can't log in. They call your number. Nobody picks up because it's 2am. They churn.
You're a sales lead. Someone just signed up for your product. By the time your team calls them back tomorrow morning, they've already picked a competitor.
You're a clinic manager. Ten patients no-showed today. Your front desk spent two hours leaving voicemails that nobody listened to.
These aren't hypotheticals. They're the daily reality of running a business where the phone still matters. And the phone still matters for a lot of businesses.
AgentLine fixes this by making phone calls just another text channel for your AI agent.
How It Works
The model is simple: your AI agent reads text and writes text. AgentLine handles everything about the actual phone call.
When someone calls your agent's number:
- AgentLine answers the call
- It captures the caller's speech and transcribes it to text
- The text goes to your AI agent — same as any other message
- Your agent processes it and responds with text
- AgentLine converts that text to speech and plays it to the caller
- This loop continues until the call ends
Your agent never touches audio. It doesn't know about WebSockets, audio codecs, or SIP protocols. It just reads and writes text. AgentLine is the bridge between that text and the phone network.
For outbound calls, it's the same flow in reverse. You tell AgentLine who to call and what to say. It dials the number, speaks the greeting, and pipes the conversation transcript back to your agent.
What's Actually in the Box
AgentLine isn't just a thin wrapper around Twilio. It's a complete telephony stack purpose-built for AI agents:
- Phone numbers: Provision US numbers in any area code. One click. $2.00 one-time. No monthly fees, no contracts.
- Voice calls: Inbound and outbound. Natural conversation with your AI agent. Per-minute billing at $0.10/min — that's speech-to-text, text-to-speech, and the carrier costs all bundled.
- SMS: Every number handles both voice and text. Inbound SMS arrives in your event mailbox. Great for order confirmations, appointment reminders, and two-factor codes.
- Voices: Multiple voice presets (female-1, female-2, male-1) plus support for any Cartesia voice UUID. Set a default or override per-call.
- System prompts: Your agent's personality, instructions, and boundaries — all defined in a prompt. Update it anytime. No redeployment needed.
- Event mailbox: A polling-based event system that delivers call completions, transcripts, and inbound SMS to your agent. No webhooks to configure. No infrastructure to maintain.
- Transcripts: Every call is transcribed end-to-end. Searchable. Reviewable. Useful for debugging prompts and improving call quality.
- Billing dashboard: Real-time balance, expenditure breakdowns by category, per-call costs, and spending trends. Know what you're spending before it surprises you.
Why Not Just Use Twilio?
This is the question we get most often. Twilio is the 800-pound gorilla in telecom. Why not just use it directly?
The short answer: Twilio was built for human call centers, not AI agents. It's a powerful, flexible telecom API — but that power comes with complexity that AI agent builders don't need.
Server Config
{
"mcpServers": {
"agentline": {
"url": "https://api.agentline.cloud/mcp",
"headers": {
"Authorization": "Bearer <YOUR_AGENTLINE_API_KEY>"
}
}
}
}