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Bidirectional Streams

Bring your own bot.
We answer
the phone.

Every call becomes a WebSocket. Speak the Twilio Media Streams protocol and your Pipecat bot runs unchanged.

Start building Read the docs
CallerAny phone, any carrier
+1 (415) 555-0134 · Connected 00:42 Connected · 00:42
SIP · RTP your number · SIP trunk
FonosterTelephony + streams
AudioRaw frames, mark, clear
SpeechSTT, TTS, turn events
ControlDTMF, transfer, hold, hang up
WebSocket wss://bot.acme.com/ws
Your botPipecat, Autopilot, your code
→↓start callSid=CA7f…
→↓media inbound · μ-law
←↑media payload=…
←↑mark reply-1
→↓dtmf 5

Speaks what your bot already speaks

  • Pipecat
  • Twilio Media Streams
  • Autopilot
  • Python
  • TypeScript
  • Any WebSocket
Twilio Media Streams compatible

Your Pipecat bot. Unchanged.

Fonoster speaks the protocol your bot already uses. Point a number at it and take the call.

Fonoster Fonoster +1 (415) 555-0134 app: support-bot
phone WebSocket · protocol: twilio bot
  1. connected
  2. start callSid=CA7f… μ-law 8 kHz
  3. media inbound "Hi, I need to reschedule"
  4. media "Sure, which day works?"
  5. mark reply-1
  6. media inbound "Actually—"
  7. clear
  8. mark reply-1
  9. dtmf 5
  10. stop
Pipecat Pipecat TwilioFrameSerializer wss://bot.acme.com/ws
Zero code changes Keep your serializer and pipeline. Only the number changes.
Barge-in that works clear and mark behave exactly as your bot expects.
Hang up from the bot auto_hang_up works through a Twilio-compatible endpoint.
Quickstart

Point a number
at a URL.

An app is a WebSocket URL and a protocol. Create it, then point a number at it. Calls open a socket to your bot.

Terminal
$ fonoster applications:create \
--name support-bot \
--url wss://bot.acme.com/ws \
--flavor twilio # or native
✔ Application created: 7f3c9a…
$ fonoster sipnet:numbers:update 2b81e4…
? Application support-bot
? Ready? Yes
✔ Done!

Grows with every call.

Scale without rewrites Your first call or your busiest day. Same app, same code.
Built for real-time Audio takes the shortest path from the caller to your bot.
Calls stay up Upgrade and scale out without dropping live calls.

Your bot,
on the phone.

Start building Read the docs