No waitlist — POST /api/v1/signup is live right now

Phone calls as an MCP tool

Give Your AI Agent a Phone Line

CallMCP is an MCP server that lets AI agents make and receive phone calls — outbound calls, appointment confirmations, lead qualification, voicemail, transcripts, and human handoff — through the same tool-call contract your agent already speaks.

Connect your agentRead the docsSee an example call

Speaks MCP — the open protocol Claude and other MCP-compliant clients already use, so there's no bespoke integration to write.

Connect in one block — no bespoke integration

{
  "mcpServers": {
    "callmcp": {
      "type": "streamable-http",
      "url": "https://callmcp.ai/mcp",
      "headers": { "Authorization": "Bearer kc_live_..." }
    }
  }
}

No key yet? Get one programmatically — a real POST /api/v1/signup your agent can call itself, with x402 machine payment or a human checkout fallback.

Illustrative example — no live call placed

Outbound → +1 (555) 123-4567completed

Called to confirm Thursday 2pm appointment. Reached voicemail on the first attempt; live pickup on retry. Confirmed the slot and sent parking instructions by SMS.

"Yes, Thursday at 2 works for me — do you have parking?"

call_3f9a1e2b94sagent: Front Deskget_transcript / get_call_recording

How a call flows through CallMCP — connect, discover, call, read the outcome

Every line of JSON in that walkthrough is the real shape — the same initialize/tools/list handshake and make_call example used elsewhere on this page. Run it yourself against the production endpoint:
curl -s -X POST https://www.kaicalls.com/api/mcp -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

What it does

Most agent frameworks can browse, read files, and call APIs. They can't pick up a phone — and a phone call needs more than a REST request/response cycle gives you for free. It needs permissions (who is this agent allowed to call, and about what), state (is the call still ringing, did it fail, was a human handed off), logs (what was said, was it recorded), and approval (should a human confirm before the agent dials). That shape — permissioned, stateful, logged, approvable — is exactly what MCP tools are for. CallMCP is built on that primitive: it exposes calling, texting, and phone-number management as MCP tools, so an agent can dial a lead, leave a voicemail, confirm an appointment, or escalate to a human — the same way it already calls any other tool.

How a call happens

An agent placing an outbound call looks like any other MCP tool call:

{
  "method": "tools/call",
  "params": {
    "name": "make_call",
    "arguments": {
      "agent_id": "agt_9f2a1c",
      "to": "+15551234567",
      "context": "Confirm Thursday 2pm appointment",
      "lead_id": "lead_88213"
    }
  }
}

The response includes a call ID, provider status, and — once the call ends — a transcript, recording URL, and outcome, retrievable with get_transcript and get_call_recording.

Everything the tool surface covers

51 MCP tools today, grouped by what an agent builder actually reaches for. Every schema below is the real inputSchema/outputSchema pair the server publishes, so a model reading this page and a model calling tools/list land on the same shape. The machine-readable version of this whole page lives at /llms.txt.

make_call({ agent_id, to, context })
// → { success: true, call: { id, status: "queued" } }

search_available_numbers({ area_code: "415" })
// → { available_numbers: ["+14155550101", ...] }
buy_number({ phone_number: "+14155550101" })
// → spends real money — carrier-billed on call

send_sms({ from_agent_id, to, message })
// gated: opt-out / DNC / quiet-hours + rate limit
// → { success: true, message_sid, to, from }

transcript_available: false
// call still in progress
transcript_available: true
transcript: "AI: Hi, this is..."

set_webhook({ webhook_url, events: ["call.completed"] })
// → { webhook_secret } — shown once, on creation
POST webhook_url
X-KaiCalls-Signature: t=1751..,v1=<hmac-sha256>

idempotency_key: required
authority: human_confirmed
  | dashboard_session | system_policy
// or queue_for_approval: true

upsert_lead({ updates: [
  { id: "lead_88213", status: "qualified" }
] })
// → { operation: "update", updated: 1, failed: 0 }

Plus agent and voice management (list_agents, create_agent, list_voices, get_business_info, get_operational_settings), voicemail (list_voicemails), business-alert config (configure_staff_alerts, configure_textable_links), campaigns (list_campaigns, create_campaign, list_workflow_templates), a knowledge base (list_knowledge, upsert_knowledge), a product catalog (list_products, upsert_product), analytics and usage (get_analytics, get_usage, get_balance, list_subscription_history, list_overage_charges, list_rightsize_recommendations), observability (list_observability_events, list_tool_execution_logs), and eval tooling (list_evals, run_eval) — 51 tools total, all discoverable via tools/list before you write a line of integration code.

Native to the core

voice.voiceId: "rachel" → "matthew"
first_message: unchanged
transfer_enabled: unchanged

Use cases

• Call leads with an AI agent — qualify or follow up, then write results back to your CRM.
• Appointment confirmation calls — reduce no-shows with confirmation and rescheduling logic.
• Missed-call recovery — when a business misses a call, your agent calls or texts back and books the next step.
• Human handoff — escalate to a person when confidence is low or the caller needs one.

Get a key

Your agent gets tools to search and buy numbers, place and receive calls, send SMS, fetch transcripts and recordings, manage webhooks, and trigger multi-step follow-up sequences — backed by the same production telephony infrastructure already carrying thousands of live business phone lines. Grab the mcpServers block near the top of this page to connect, or have your agent provision its own key by calling POST /api/v1/signup directly — no human required.