Callmcp MCP server

One MCP server. Any call provider. Fully local, fully hosted, or bring your own frontier model.

CallMCP is a single Model Context Protocol server that defines one tool contract — 14 tools, identical schemas, identical error shapes — for outbound/inbound telephony: calls, SMS, recordings, transcripts, and phone-number lifecycle. Point it at a hosted backend, a fully local backend, or a bring-your-own-key composed backend, and your agent code doesn't change. What changes is which tools are present (via capability-gated dynamic discovery), never the shape of a tool that's there.

The normative reference is SPEC.md. This README is the pitch; the spec is the contract.

npx -y @callmcp/server

Before connecting a real provider, run npx -y @callmcp/server doctor. For a safe local walkthrough, run npx -y @callmcp/server --sandbox. The server fails closed when no driver is configured; the mock driver is only available through explicit sandbox configuration.

See examples/ for ready-to-paste Claude Desktop / Claude Code configs for each of the three legs below.

Three structural claims

This isn't "a Twilio wrapper with a marketing page." Three things are actually built into the contract, not bolted on:

1. Provider-neutral, multi-backend contract

Every driver — hosted, local, or BYOK — implements the same 14 tools defined in SPEC.md. Driver-specific behavior lives exclusively inside a namespaced options. passthrough object. There is no makecalltwilio or makecallkaicalls. A tool either exists for your configured driver (and works, fully, per spec) or it's absent from tools/list — never present-but-broken. Swapping your call backend is a config change, not a rewrite.

2. x402-funded autonomous provisioning to production

searchnumbers, buynumber, configurenumber, and listnumbers are never human-approval-gated — they don't contact a third party, they contact your own provider account. That includes settling cost via x402 machine payments when a driver requires prepayment (INSUFFICIENT_FUNDS embeds a full x402 challenge an agent can settle and retry). An agent can search for a number, pay for it, configure it, and go live — autonomously, in production, with real money — without a human clicking anything. This is a deliberate contrast with vendor MCPs whose autonomous/self-serve paths are trial- or sandbox-scoped only.

3. Human-in-the-loop outbound approval as designed consent architecture

makecall and sendsms — anything that contacts a phone number that isn't the calling agent's own infrastructure — structurally require a valid approvalid or a standing allowlist match before they act. This isn't a policy suggestion layered on top; it's enforced in the server core, so no driver implementation can bypass it. Primary path is MCP elicitation; the fallback for non-elicitation clients is a single-use out-of-band approval URL — the gate is designed to never silently block forever and never silently open. Read as a TCPA-consent posture: the contract makes "who approved contacting this number, and when" a first-class, auditable object (requestcallapproval / listapprovals), not an assumption baked into application code you have to get right yourself.

CallMCP vs. single-vendor MCPs vs. DIY

Shortened. The full README is on GitHub.