Ringback lets Claude call your phone when an agent gets stuck
u/Kitchen-Ad5791 built Ringback, a free, self-hosted MCP server that lets Claude phone you for a live two-way voice conversation when it hits a decision point during a long-running task.
Score breakdown
Ringback closes the human-in-the-loop gap for long-running agentic tasks by replacing passive notifications with an active, two-way voice channel that lets users make decisions without returning to their laptop.
- 01Ringback is a self-hosted MCP server that lets Claude call a user's phone for a live two-way voice conversation when it gets stuck.
- 02Built in response to a real need: supervising a multi-hour Azure subscription migration without staying at a laptop.
- 03Uses the free Linphone SIP app — no Twilio, no per-minute fees, no extra API keys required.
u/Kitchen-Ad5791 built Ringback after a practical frustration: running a multi-hour Azure migration between subscriptions with Claude as the automation agent. While Claude could resolve most issues autonomously, it occasionally hit decision points — migrate a resource, recreate it, or skip it — that required human sign-off. Push notifications still meant walking back to the laptop; what was needed was a direct voice channel.
Ringback is the result: a free, open-source MCP server (Apache 2.0, hosted at github.com/mohitbadwal/ringback) that enables Claude or any MCP-compatible client to place a real phone call to the user.
Ringback is the result: a free, open-source MCP server (Apache 2.0, hosted at github.com/mohitbadwal/ringback) that enables Claude or any MCP-compatible client to place a real phone call to the user. The agent speaks the problem aloud, presents the options, and listens for a verbal response that is then injected back into the active session. Users can interrupt mid-sentence or instruct the agent to call back later. The tool also detects whether the user is already at their desk and, if so, delivers the message in chat rather than placing a call.
The stack is deliberately zero-cost: Ringback uses the Linphone app for free SIP calling and runs entirely on the user's own machine across Mac, Linux, and Windows — no Twilio, no per-minute billing, and no additional API keys required. The author's proof-of-concept moment came at 2 AM when Claude called to ask whether to proceed with migrating a specific resource; the author answered, gave the go-ahead, and went back to sleep while the migration continued.
Key facts
- 01Ringback is a self-hosted MCP server that lets Claude call a user's phone for a live two-way voice conversation when it gets stuck.
- 02Built in response to a real need: supervising a multi-hour Azure subscription migration without staying at a laptop.
- 03Uses the free Linphone SIP app — no Twilio, no per-minute fees, no extra API keys required.
- 04Runs on Mac, Linux, and Windows.
- 05If the user is at their desk, Ringback skips the call and delivers the message in chat instead.
- 06Released as open source under the Apache 2.0 license at github.com/mohitbadwal/ringback.
- 07The author's first real-world use: a 2 AM call from Claude asking whether to proceed with migrating a specific resource.
Topics
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