$3 Activation · 10 minutes of calls · use them over 14 days · 1 US numberActivate for $3
For Muse

Give Muse a phone number.

Muse can send mail, book travel, and act in the apps you connect. It cannot pick up a phone. CosVoice is the phone: a real number and email address that Muse uses on your behalf, so the places that only answer a phone are no longer out of reach.

Get your line.

Pick a number in your area code. About a minute. Activate for $3.

Make a key.

In your dashboard, open Connect your agent and create an API key. It is shown once. Keep it somewhere safe.

Hand it to Muse.

Paste the block below into Muse. When it asks for the key, use its secure prompt, not the chat window, so the key stays out of your message history.

Paste this into Muse
I have a CosVoice line: a real phone number and email address for you to use on my behalf.

Build a connector for it from the spec at https://cosvoice.com/openapi.json
Base URL: https://cosvoice.com/api/v1
Auth: Authorization: Bearer <my CosVoice API key> — ask me for the key through your secure credential prompt, never in chat.

How it works: POST /calls with "to" and "purpose" written the way I would say it, including what to accept if the first answer is no. The call takes a few minutes. Poll GET /calls/{id} until status is completed, then tell me the outcome and the details it captured.

Always ask me before you place a call, and tell me who you are about to ring and why.
What Muse can then do
  • Call a restaurant, a garage, a landlord, a doctor's office, and hold the conversation.
  • Read back what was agreed: the time, the price, the reference number, the next step.
  • Catch up on everything the line handled while you were away.
  • Send and read mail at the line's own address.
  • Teach the line who matters: approved, VIP, blocked.
Why a key and not a paste-in address

Assistants that speak MCP connect to CosVoice by pasting one address. Muse builds its own connector instead, from our published spec at cosvoice.com/openapi.json, and holds your key in its credential store. Both roads end in the same place: Muse asks, the line calls, you get the write-up.

If Muse gains one-click connectors later, the address is https://cosvoice.com/mcp and nothing else changes.

Keep one rule

Ask Muse to confirm with you before any call goes out, and to say who it is ringing and why. The line itself holds the rest of the line: it says it is an assistant whenever anyone asks, it never reads out a card number, and it will not agree to spend your money. Nothing is charged for a call you did not ask for.

Give Muse a number to call from.

A number in your area code, its own email address, and a written account of every call.

Activate for $3
Common questions

Straight answers.

Does CosVoice work with ChatGPT, Claude, Cursor, or Muse?

Yes. Any assistant that supports MCP connects with one paste: Grok Bot, Claude, ChatGPT, Cursor, and others. Meta's Muse takes a different road, because it writes its own connector: you make an API key and Muse reads our published spec at cosvoice.com/openapi.json. The steps are at cosvoice.com/muse. Any of them can be woken by CosVoice if it has a webhook URL and a token. Developers also get a REST API and signed webhooks.

Do I need a Grok Bot?

No. The line works on its own. Call it, text it, and ask it to make calls from your dashboard. If you do have a Grok Bot, or another assistant that supports MCP, connecting it lets your assistant make calls and read the summaries by itself.

Can it spend money or commit me to things?

On a call, no. It never gives out a card number or agrees to a charge, so a booking or appointment is the most it commits you to. Your plan's minutes are the only thing the line itself spends, and app orders (dinner, groceries) go through only after you confirm.

How good is the voice?

Good enough that callers treat it as a person. You pick from 38 voices in two sets, the new ones and the classic ones, and change any time in Settings. Every voice has a play button, and you can hear full calls on the demo page.

All questions and answers →

Give your Chief of Staff a phone.

Pick a number, save the contact, make the first call. About a minute.

Activate for $3