Voice gets the attention. SMS still matters.
An agent with an AgentLine number can read texts people send to that number and send texts of its own.
What Is an AI SMS Agent?
On AgentLine, an AI SMS agent is an AI agent with a real US or Canada phone number that sends and receives text messages. A person or a service texts the number. The message arrives as an sms.received event, and the same text is available from GET /v1/messages. The agent reads the sender and the body, and replies with POST /v1/messages.
The number is also the agent's voice line. One US or Canada number covers calls and texts in both directions. When a text is not enough, the agent places a call.
Can AI Agents Receive SMS?
Yes. Inbound SMS arrives as sms.received on the persistent relay, or on an HTTPS webhook if the relay is not installed. History is GET /v1/messages?limit=20.
Can AI Agents Send SMS?
Yes. POST /v1/messages with agent_id, to_number (E.164) and body sends a text from the agent's number. Add media_url for an MMS attachment, or from_number_id to send from a specific number instead of the agent's default. The response is the stored message with its delivery status; an accepted message is not yet a delivered one, so check GET /v1/messages when delivery matters.
What SMS Is For
- Verification codes: give the number to a service that texts a one-time code, then read sms.received and use the code.
- Messages a customer sends you: an order id or a question lands as text. The agent reads it and continues in your app, or calls the sender.
- Replies, confirmations and reminders: the agent texts back with POST /v1/messages instead of placing a call.
- A record of what was sent and what arrived, via GET /v1/messages.
Follow-ups that need a conversation still go out as voice calls. Calls are $0.12 per minute, per-second after a one-minute minimum.
How SMS Works
- Provision a US or Canada number with POST /v1/numbers and country US or CA. It is included in your plan; additional numbers are $3.00/month.
- When someone texts that number, AgentLine stores the message and emits sms.received.
- The agent reads the event, or lists history with GET /v1/messages?limit=20.
- To reply or to reach someone by text, the agent calls POST /v1/messages with agent_id, to_number and body.
Pricing and Limits
- Phone numbers: included in your plan; $3.00/month each beyond it. US and Canada.
- Voice calls: $0.12 per minute, per-second after a one-minute minimum.
- SMS: plans include an allowance for sent and received texts; beyond it each message is $0.02 in either direction. If a text includes a picture, the message stores the carrier media URL.
- API keys: al_live_ (legacy sk_live_ still works), sent as Authorization: Bearer.
- MCP: https://api.agentline.cloud/mcp via npx mcp-remote and a Bearer token.
Getting Started
Sign up at agentline.cloud/signup, create an agent, provision a US or Canada number, and install the skill at agentline.cloud/skill.md. SMS in both directions is available on that number as soon as it is provisioned. The skill file is the source of truth if this guide and the product ever disagree.