call4me: MCP server for making phone calls
call4me is a remote MCP server for making phone calls. Point any MCP client at https://call4.me/mcp
(streamable HTTP) and your agent can phone a business for you. One-line install for Claude Code:
claude mcp add --scope user --transport http call4me https://call4.me/mcp
call4me lets your AI agent make real phone calls for you. Ask Claude, ChatGPT, Cursor, Codex or your own app to book a table, schedule a dentist appointment, cancel a subscription or ask a business a question, and it calls, waits on hold, gets through the phone menu, talks to the person who answers and reports back with the outcome and a transcript. It can also ring you to join the call. Calls are paid from prepaid credits, starting at $10.
Use it
The hosted MCP server is https://call4.me/mcp (streamable HTTP). Your agent signs you in through the
browser with Google or X. The easiest setup is to paste the prompt from call4.me/mcp
into your agent. To add it by hand:
claude code: claude mcp add --scope user --transport http call4me https://call4.me/mcp then /mcp, call4me, authenticate
codex: codex mcp add call4me --url https://call4.me/mcp then codex mcp login call4me
claude desktop / claude.ai / chatgpt: settings, connectors, add custom connector: https://call4.me/mcp
can't sign in? create a key at https://call4.me/account and use https://call4.me/mcp/<key>, or send "Authorization: Bearer <key>" to /mcp
Cursor: add it to ~/.cursor/mcp.json and sign in when Cursor asks.
{
"mcpServers": {
"call4me": { "url": "https://call4.me/mcp" }
}
}
In your own code, the Vercel AI SDK package gives an agent the same tools:
npm install call4me-ai-sdk ai zod @ai-sdk/openai
import { call4meTools } from 'call4me-ai-sdk';
// with CALL4ME_API_KEY set (from https://call4.me/account):
// generateText({ model, prompt: 'Call ... and ask ...', tools: call4meTools() })
- Examples: real calls and the prompts that placed them.
- Blog: guides for Claude Code, the AI SDK and more.
- MCP Registry:
io.github.skeptrunedev/call4me.
The rest of this README is for working on call4me itself or hosting your own copy.
How a call works
agent ──MCP──▶ worker ──POST /v2/calls──▶ Telnyx ──PSTN──▶ business
▲ │ media stream (PCMU, bidirectional RTP)
│ webhooks ▼
└──────────────── VoiceSession (Durable Object) ◀──WS──▶ GPT-Live (gpt-live-1, audio/pcmu 8k)
└─ back office (Responses model):
end_call · ask_user · press_digits
src/server/voice/prompt.ts: what the caller is told. The product lives here: no opening disclosure, no recording notice, no end-of-call read-back; honest if sincerely asked whether it's an AI.src/server/voice/session.ts: the audio relay and back-office functions.src/server/services/dialer.ts: placing calls, per-account numbers, answering callbacks.src/server/services/numbers.ts: the account's call4me numbers, and the user's own numbers verified to call from. Telnyx keeps one verified-number list for our whole carrier account, soverified_numbersties each to the one call4me account that submitted a fresh code for it; a number Telnyx already lists as verified is never handed to another account. A call from an own number (from) only reaches businesses in its country, and still rings the user from a call4me number.src/server/mcp/server.ts: the MCP tools.
The app does not request recording when dialing or answering. Existing recordings stored by Telnyx
can be played or opened from the signed in call page after a call ends, or retrieved using call4me_get_recordings({ call_id }) over MCP, or
GET /api/calls/{call_id}/recordings with a call4me API key or OAuth token in the Bearer header.
Both check account ownership before contacting Telnyx and return fresh download links without
storing them. Empty results can mean processing is pending or no recording was saved. Links may
expire and should only be shared with the account owner.
Trunk recordings use call leg IDs. A separate provider ID table receives these from verified webhooks; existing calls resolve them from an exact control ID match in Telnyx webhook history. The app never guesses a match from phone numbers or timestamps. If provider history has expired and no mapping was saved, only recordings directly associated with the control ID can be found.
The recording lookup never contacts the voice session or changes prompts, live tools, audio, or Telnyx recording settings. Existing call status and transcript responses are unchanged.
The recording API's OpenAPI document is served at /api/openapi.json. Run
npm run openapi:generate to regenerate openapi.json from the shared MCP and HTTP schemas.
CI checks the generated artifact for drift. Run npm test, npm run check, npm run lint,
and npx wrangler deploy --dry-run before deploying through git.
Menu recovery tracks fresh phone prompts separately from transcript timestamps and remembers accepted keypad submissions. Repeated menus, invalid input, and recorded instruction dead ends can restart the existing back office after the recording goes quiet. It waits for pending tools and their continuations, avoids interrupting holds or a person answering, and asks the model to choose a supported route from the heard options rather than blindly replaying digits.
npm test includes provider message replay tests for recovery and its timing races. To evaluate
the configured back office model against synthetic menu scenarios, run npm run test:menu:live
with OPENAI_API_KEY (or a local .dev.vars). This opt-in evaluation calls OpenAI, inspects
the proposed tool calls, and never executes a tool or places a phone call.
Setup
- Telnyx: a Call Control application (its id is
TELNYX_CONNECTION_ID) with webhook URLhttps://<host>/webhooks/telnyx, an API key, and the account's webhook public key. Each account's number is bought on its first call and attached to that application. - OpenAI: an API key with GPT-Live access.
- Stripe: webhook endpoint
https://<host>/webhooks/stripeforcheckout.session.completed,checkout.session.async_payment_succeeded,invoice.paid,customer.subscription.updated,customer.subscription.deleted,charge.refunded. The blog's supporter subscriptions arrive on the same endpoint, taggedapp=callbay, kind=supporter(seesrc/server/services/supporters.ts).
Credits
Everything is prepaid. Loads start at $10 and, by default, the same amount reloads monthly (a Stripe
subscription; invoice.paid adds the credits). A call holds its maximum cost before it dials, in one
conditional insert so parallel calls can't overspend, and settles to the real talk time when it ends.
4. Secrets (wrangler secret put): see src/server/env.d.ts.
Two Workers
Call sessions run in their own Worker, call4me-voice (wrangler.voice.jsonc, src/server/voice/worker.ts),
which also takes Telnyx's media streams on voice.call4.me. Deploying a Worker resets the durable objects it
defines, so with the sessions split out the site deploys freely without dropping a call. CI deploys the voice
Worker with scripts/deploy-voice.sh, which skips an unchanged bundle and otherwise waits until no call is up,
deploys, and holds new calls until the new version is serving plus a minute for Cloudflare to retire the old
one. Never deploy it or change its secrets any other way: either restarts every live call. The voice Worker's secrets are
OPENAI_API_KEY, TELNYX_API_KEY, TELNYX_CONNECTION_ID, RAINDROP_WRITE_KEY and STREAM_SECRET (the same
value as the site's): npx wrangler secret put <NAME> -c wrangler.voice.jsonc.
Crawlers
/robots.txt allows every crawler on every path, including AI search, answers, and training.
The wildcard covers current and future crawlers without maintaining a named allowlist.
Cloudflare's desired crawler settings live in cloudflare.crawlers.json. Run npm run crawlers
to audit them, or npm run crawlers -- --apply to apply and verify them. The command requires
CLOUDFLARE_API_TOKEN with Zone Read, Zone Settings Read and Write, and Bot Management Read
and Write for call4.me. Any unavailable or mismatched setting fails the command. Separately
audit AI Crawl Control and firewall rules for crawler blocks. Cloudflare's automatic DDoS
protection remains active.
If an account token can manage tokens but lacks the permissions on this zone, use
npm run crawlers -- --apply --authorize to add the necessary permissions for call4.me.
It discovers permission IDs from Cloudflare and preserves existing permissions and restrictions.
The token editor calls Write permissions Edit. Account tokens may be unsupported by some bot
products; use a user token from My Profile if Cloudflare rejects a correctly scoped account token.
To manage another site's committed policy, pass --policy /path/to/cloudflare.crawlers.json.
Public page delivery
npm run build:site renders public HTML and Markdown from the existing Hono views into
dist/site, copies the public assets, and fingerprints CSS and JavaScript. Wrangler runs
this build automatically before local development, dry runs, and deployments. CI also
builds before checking the generated route manifest and tests. No database or credentials
are used to generate public pages. Paid articles are excluded from the static manifest.
src/server/static-entry.ts serves these documents through Cloudflare's cached asset
binding without initializing the application or reading D1. CSS, images, and scripts go
straight to static asset delivery. Native page transitions progressively enhance ordinary
navigation and honor reduced motion. Audio keeps the byte range handler needed for seeking.
Public content is identical for every viewer. Account navigation, counts, and escaped blog
comments load after the page paints from private, uncached live endpoints. Search, top
sorting, subscription feedback, authenticated MCP setup, accounts, payments, OAuth, and
all writes still use the existing server. ?live=1 opens the dynamic page when JavaScript
is disabled or live comments cannot load. First touch cookies remain per visitor; a paid
Reddit landing records its attribution before issuing the visit cookie.
Blog
/blog is markdown files in src/content/blog (one per post, listed in index.ts, headline image at
public/static/blog/<slug>.svg), with an Atom feed, likes, comments, an email newsletter (sent from
/admin/blog, for the ADMIN_EMAILS accounts), and paid posts for monthly supporters.
Related articles use local CPU embeddings, ranked within editorial subjects from
scripts/related-topics.ts. After adding an article or changing its SEO title, tags or subject,
run npm run blog:related, review the matches in src/content/blog/related.generated.ts, and
commit the index. The first run downloads the pinned EmbeddingGemma model; later runs use
~/.cache/call4me/transformers. Article text stays local. The site serves the generated index
without model inference. Articles can have fewer than three recommendations when matches
fall below the similarity threshold. npm test checks freshness without downloading a model.
Self-hosting
Fork it, create your own D1 database (wrangler d1 create callbay) and put its id and your own hostname in wrangler.jsonc.
Local: npm run db:migrate:local && npm run dev with a .dev.vars holding the same secrets.
AI monitoring
Raindrop monitors the live conversation (callbay_voice_call), back office model runs
(callbay_back_office), and the recap after hangup (callbay_call_recap). Each event uses
the account ID as its user ID and the call ID as its conversation ID. Model names, timing,
status, and back office tool spans are included. No phone audio or recording URLs are uploaded.
Add RAINDROP_WRITE_KEY to .dev.vars locally and configure the same key as a Cloudflare
Worker secret with npx wrangler secret put RAINDROP_WRITE_KEY. Optional
RAINDROP_PROJECT_ID selects a project slug; unset uses the write key's default project.
Without a write key, monitoring is disabled. .dev.vars.example lists these optional settings.
AI inputs and outputs use Raindrop's PII redaction, with call4me's existing masking for per call secrets applied first. Tool arguments and results appear in redacted back office AI output. Tool spans contain names, timing, and generic failure status, keeping sensitive payloads out of unredacted trace attributes. Account names and emails are not sent as user traits. SDK PII redaction is pattern based and does not guarantee removal of every sensitive detail.
Monitoring runs separately from live audio and tools. Terminal events and queued tool spans are flushed within the Worker or Durable Object lifetime. An unfinished back office run at hangup is marked interrupted; later tool results do not reopen the closed monitoring client.
After a call, check the three event names in Raindrop, with actual inputs and outputs, the matching account and call IDs, and tool names and durations. A call that never invokes a back office model has no back office event. Feedback signals, audio attachments, and agent self diagnostics are not instrumented because the current call flow has no corresponding feedback controls or diagnostics tools.
For investigation, connect the Raindrop MCP server and install
the investigation skill with npx skills add raindrop-ai/skills --skill raindrop-investigate.
Connect Slack in Raindrop for alerts. Create a Raindrop account if needed.
License
MIT
