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Your agent must already be connected to Tuner and sending real calls, with its Call Direction set to Inbound.
For inbound simulation, Tuner calls your agent the same way a phone call reaches it. For most platforms that means a SIP URI Tuner can call, plus a username and password if your SIP endpoint requires them.

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Find your platform

Every platform except Retell ends the same way: you paste the SIP URI into the SIP Settings card in Agent Settings > Simulation Setup and click Verify & Save. Tuner places a short test call to check the connection. Tuner Agent Settings, SIP Settings (SIP URI, username, password)

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Retell

Retell agents need no setup. Tuner starts each simulation call through Retell, using your agent’s Agent Remote ID and the Retell API key saved on its integration, so there’s no SIP URI and the SIP Settings card isn’t shown. Retell supports inbound simulation and replays. Outbound simulation isn’t available for Retell agents.

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Vapi

1

Create a free Vapi SIP trunk

  1. Open the Vapi dashboard and go to Phone Numbers.
  2. Click Create Phone Number and choose Free Vapi SIP.
  3. Fill in the SIP Identifier (it becomes part of your SIP URI), a Label for your own reference, and a Username and Password.
  4. Click Import SIP URI.
Your SIP URI is sip:<SIP Identifier>@sip.vapi.ai.Creating a Free Vapi SIP trunk (Phone Numbers > Free Vapi SIP)
Save the username and password now. Vapi shows the password only once. If you lose it, delete the trunk and create a new one.
2

Link your assistant

Simulation calls won’t connect without this step.
  1. In Phone Numbers, click your SIP trunk.
  2. Under Inbound Settings, set Assistant to the assistant Tuner should reach.
  3. Click Save. Link your Vapi assistant to the SIP trunk in Inbound Settings
3

Paste it into Tuner

In Agent Settings > Simulation Setup, in the SIP Settings card, enter the SIP URI. Under Authentication (optional), enter the Username and Password from the first step. Click Verify & Save.

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Dograh

Before you start:
  • Dograh v1.48.0 or later. Earlier versions don’t reliably send Tuner the SIP call ID, so simulation calls can land in Call Logs as production traffic instead of linking to their run.
  • The Tuner node enabled on your Dograh workflow, and the workflow published. Inbound calls run the published version, so a Tuner node that exists only in a draft sends nothing to Tuner. See Connecting to Dograh.
  • In Dograh, a phone number under Telephony configurations > Dograh Cloudonix SIP > Phone numbers with its Inbound workflow set to your agent. A short extension such as 101 works; it doesn’t need to be a real number. See Dograh’s SIP guide if you haven’t set one up.
1

Build the SIP URI

The URI is sip:<address>@<hostname>:For example: sip:101@a1b2c3d4-0000-0000-0000-9f8e7d6c5b4a.sip.cloudonix.net. If the UDP/TCP port under SIP connectivity isn’t 5060, add it to the end, for example sip:101@<hostname>:9060.
2

Paste it into Tuner

In Agent Settings > Simulation Setup, in the SIP Settings card, enter the SIP URI. Dograh’s inbound endpoint doesn’t use SIP authentication, so leave Username and Password empty. Click Verify & Save.
Known issue. With both authentication fields empty, verification can fail with “endpoint did not answer.” Enter any placeholder values, for example tuner and tuner. Dograh never checks them.

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LiveKit, Pipecat and custom stacks

1

Get your SIP URI

Use the SIP URI and credentials from your phone or SIP provider. SIP providers covers Twilio, Telnyx, Plivo, Exotel, Jambonz, Daily and LiveKit SIP.
2

Paste it into Tuner

In Agent Settings > Simulation Setup, in the SIP Settings card, enter the SIP URI. If your SIP endpoint uses digest authentication, open Authentication (optional) and enter the Username and Password. Otherwise leave them empty. Click Verify & Save.
3

Add the simulation step to your integration

Your integration has to send each call back with the ID Tuner put on it, so Tuner can link the call to the run. Follow Enable simulation on your LiveKit, Pipecat or custom stack integration page. On LiveKit, the SDK does this for you.

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Check it works

Follow Run your first simulation. If calls show Unreported, the call reached your agent but didn’t link back to the run. See Fix an Unreported run. Replays of your Dataset calls reach your agent the same way, so once simulations connect, replays will too. Replays also work with outbound simulation.

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How SIP works

You don’t need this to set up simulation. It helps when a call doesn’t connect.
SIP (Session Initiation Protocol, RFC 3261) is the protocol voice platforms use to start, manage and end calls. Tuner uses it so simulated calls reach your agent through the same path as a real phone call: the same audio pipeline, transcription, prompt and tools.
  1. Tuner sends a SIP INVITE to your SIP URI. It carries a SIP Call-ID and an X-Correlation-Id header that Tuner generated for this call.
  2. If your SIP endpoint uses digest authentication, it replies with a 407 Proxy Authentication Required challenge, and Tuner sends the INVITE again with your username and password.
  3. Your endpoint accepts the call and passes it to your agent. Audio flows both ways, and to your agent it’s a normal inbound call.
  4. When the call ends, your integration sends it to Tuner with one of those IDs, and Tuner links it to the run. See How simulated calls are linked.
A typo in the URI sends the INVITE to the wrong place, and wrong credentials fail the 407 challenge. Either way, the call never connects.
  • sip:: the scheme, like https:// for web addresses. You may see sips: for SIP over TLS; paste it as shown.
  • user-part: an identifier your provider assigns, such as Vapi’s SIP Identifier or a Twilio or Telnyx credential username. Sometimes there isn’t one and the host is enough.
  • host: the public address of your SIP endpoint, for example sip.vapi.ai, sip.telnyx.com or your-project.sip.livekit.cloud.
A URI can also carry parameters after the host, such as ;transport=tcp. Copy whatever your provider’s console shows.

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Next steps

Run a simulation

Every option in the Run Simulation dialog.

Run statuses

What each run status and call result means.