Make phone calls from Muse with Prism

In this guide, you’ll connect Rime Calls, the connector that lets Muse place phone calls, and have Prism make a call for you. It takes about two minutes, and you don’t write any code. You tell Muse what you need and approve the call. Prism, Rime’s speech-to-speech model, talks to the business, and Muse shows you a report when the call ends.

What you’ll need

A Muse account.
A Rime API key with access to Prism. If you don’t have one yet, sign up for Rime to create one.

You don’t need a Twilio account or a phone number. Calls go out from a Rime phone number, and Rime covers the line.

Connect Rime Calls

Copy the setup message

This message tells Muse how to build the connector. Copy it as is:

Setup message

Add a custom connector for me so you can make phone calls on my behalf with Rime Prism.

- Slug: rime-calls
- Endpoint: https://muse-connector-m3jasmbv4a-uk.a.run.app/mcp (MCP server, streamable HTTP)
- Auth: a static API key, sent as "Authorization: Bearer <key>". The key is my Rime API key. I'll enter it on your secure page, never in chat.
- Tools:
  - start_call places a real phone call to a business for me. It's a sensitive write: ask for my approval every time, showing who you'll call and every detail you'll send.
  - get_call reads a call's status and its report.
  - hang_up ends a call I started.

When you call start_call, always fill in on_behalf_of with my name, and may_agree_to with exactly what I said you can agree to. If the business might ask for a callback number, ask me for one and put it in context.

After setup, list the tools to confirm the connection works.

Paste it into Muse

Start a new chat in Muse and paste the message. Muse builds the connector and shows a Connect button under “Rime Calls”.

Enter your API key

Select Connect, and paste your Rime API key on the page Muse opens.

Enter your key only on Muse’s Connect page, never in the chat. Anyone who has your key can use your Rime account.

Always allow Rime Calls

When Muse asks to share information with muse-connector-m3jasmbv4a-uk.a.run.app, choose Always allow this site. With Allow once, Muse asks again before every request, and setup times out while it waits.Muse then lists three tools: start_call, get_call, and hang_up. Rime Calls is ready.

Make your first call

Ask a local business when it’s open. It’s a short call with nothing to agree to, so it’s a good first test:

Call [business name] at [phone number] and ask what their hours are this weekend. My name is [your name].

Muse shows you who it’ll call and what it’ll say, and waits for your OK. When you approve, Prism dials, and Muse shows you the report once the call ends.

What Prism does on a call

Prism follows the same rules on every call:

It says who it is. Early in the call, it says it’s an AI assistant calling for you, and that the call is transcribed.
It sticks to your details. It uses only what you gave Muse and never makes anything up.
It agrees only to what you allowed. Anything outside may_agree_to, it declines or brings back to you. It never gives payment details.
It waits on hold. If the business puts the call on hold, Prism stays on the line and waits.
It leaves a message. If it reaches voicemail, it leaves a short one.
It respects “don’t call again”. If the business asks not to be called, Rime Calls won’t call that number again.

What you get back

When the call ends, Muse reads the report with get_call and shows it to you:

Part	What it tells you
Result	Done, partly done, not done, voicemail left, no answer, or failed
Summary	What happened, in a few sentences
Facts	What Prism learned, such as hours, prices, or a confirmation number
Commitments	What Prism agreed to for you, and whether each one was within what you allowed
Next steps	Anything you need to do
Open questions	Questions the business asked that Prism couldn’t answer

Limits

Limit	Value
Who Rime Calls can call	Business lines (landline, VoIP, or toll-free) in the US and Canada. Personal cell phones are refused.
When	9:00 to 20:00 in the business’s local time
Calls per API key	20 calls and 60 connected minutes a day
Calls to one number	2 a day across all Rime Calls users, or 20 for a toll-free number
Length of a call	5 minutes unless Muse asks for more, up to 30. Recipes for calls that may involve a hold ask for more.

If Rime Calls is busy when Muse places a call, it asks Muse to try again in about 10 minutes.

Who pays

Prism usage on the call counts toward your Rime account. Rime covers the phone line and the call report.

Your data

Rime Calls never stores your API key. Your calls are tied to a fingerprint (hash) of the key, so only your key can read them.
Call details, transcripts, and reports are deleted after 30 days. No audio is kept.

For more, see Rime’s privacy policy.

Troubleshooting

Muse passes on the reason when Rime Calls can’t place a call. These are the reasons, and what to do:

The reason says	What to do
Muse can’t connect, or setup times out	Choose Always allow this site, and check that you entered your key on Muse’s Connect page
”egress request denied” or “policy_denied”	Muse is blocking the connector. Remove Rime Calls in Muse, paste the setup message again, and choose Always allow this site
”Check that the Rime API key has access to Prism”	Your key was accepted, but it can’t use Prism. Check your account at app.rime.ai.
”this looks like a personal cell phone”	Use the business’s main line. Rime Calls calls business lines only.
”calls go out between 9:00 and 20:00 in the callee’s local time”	Ask again during the business’s daytime. The message says when the next window opens.
”every line is busy”	Wait about 10 minutes and ask again
”this number has already been called 2 times today”	Try tomorrow, or call them yourself
”this number asked not to be called”	The business opted out of calls. Call them yourself.
”this Rime key’s daily call limit is used up” or “daily minutes are used up”	Your key has used its 20 calls or 60 minutes for the last 24 hours. Try again tomorrow.
A call never returns a report	Ask Muse to check the call again, in the same conversation. Only that conversation has the call’s ID.

Use Rime Calls from another agent

Rime Calls is an MCP server, so any agent that supports remote MCP servers can use it. Connect to https://muse-connector-m3jasmbv4a-uk.a.run.app/mcp over streamable HTTP, and send your Rime API key as Authorization: Bearer <key>. This command adds it to Claude Code:

claude mcp add --transport http rime-calls https://muse-connector-m3jasmbv4a-uk.a.run.app/mcp --header "Authorization: Bearer $RIME_API_KEY"

The tool reference describes start_call, get_call, and hang_up in full. Every recipe below works the same way in any agent with Rime Calls connected.

Try a recipe

Each recipe is a message you fill in and paste into Muse. Start with the first one:

Ask a business its hours

A short first call that checks your setup.

Book a table

Book within the times you allow.

Book a haircut

Book within your times, stylist, and price.

Move or cancel a reservation

Change hotel, restaurant, or salon bookings.

Ask a hotel about rates

Get the real total, fees, and policies.

Check stock and hold an item

Make sure it’s there before you drive over.

Get started

Build with Rime

Integrations

Account & updates

Make phone calls from Muse with Prism

What you’ll need

Connect Rime Calls

What Prism does on a call

What you get back

Limits

Who pays

Your data

Troubleshooting

Use Rime Calls from another agent

Try a recipe

Ask a business its hours

Book a table

Book a haircut

Move or cancel a reservation

Ask a hotel about rates

Check stock and hold an item

​What you’ll need

​Connect Rime Calls

​What Prism does on a call

​What you get back

​Limits

​Who pays

​Your data

​Troubleshooting

​Use Rime Calls from another agent

​Try a recipe

Ask a business its hours

Book a table

Book a haircut

Move or cancel a reservation

Ask a hotel about rates

Check stock and hold an item

What you’ll need

Connect Rime Calls

What Prism does on a call

What you get back

Limits

Who pays

Your data

Troubleshooting

Use Rime Calls from another agent

Try a recipe