Additional Cost

SIP calls are currently free of charge while in preview but will incur an additional charge when it moves to full release.

Session Initiation Protocol (SIP) enables Ultravox agents to connect with your existing phone systems and SIP clients. This guide explains how to set up both incoming and outgoing SIP calls with Ultravox agents.

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SIP Quickstart

The fastest way to start using SIP with Ultravox:

1

Create an Agent

Create an agent using the Ultravox Realtime console.
2

Create a SIP Call

Create an agent call using the Create Agent Call API and use the sip medium.
API Key Required

Make sure you have an Ultravox API key. You can create one in the console.

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SIP Overview

Ultravox uses a medium for each call, which defines how the call will occur. When using sip as the medium, you can connect your Ultravox agents with standard SIP-compatible systems.

You can create a SIP call with the Ultravox Realtime Create Agent Call or Create Call endpoints using the sip medium.

The sip medium supports the creation of both incoming and outgoing calls.

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Incoming SIP Calls

Incoming calls are initiated by a SIP client to your Ultravox agent. When the Ultravox incoming SIP call is created, the returned join URL is a SIP URI to which an invite can be sent.

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Outgoing SIP Calls

Outgoing calls are when Ultravox initiates the call to a SIP endpoint or client. The configuration varies slightly depending on which SIP client/system you’re using.

When creating an outbound SIP call, Ultravox will initiate the call directly and no join URL will be returned.

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Create an Outgoing SIP Call

For outgoing SIP calls, you’ll need to add the outgoing configuration data for the sip medium and add it to the request body of the Create Agent Call or Create Call request:

medium: {
  sip: {
    outgoing: {
      to: "sip:<destination>@<sip_domain>",
      from: "<your_identifier>",
      username: "<authentication_username>",
      password: "<authentication_password>"
    }
  }
}

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Linphone Example

Example: Creating an Outgoing SIP Call to Linphone
    medium: {
      sip: {
        outgoing: {
          to: "sip:<username>@sip.linphone.org",
          from: "<company_name>"
        }
      }
    }

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Create an Incoming SIP Call

For incoming SIP calls, you’ll need to use incoming for the sip medium and add it to the request body of the Create Agent Call or Create Call request. This will return a joinUrl that can be used to connect to a SIP client.

Example: Creating an Incoming SIP Call
medium: {
  sip: {
    incoming: {}
  }
}

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Supported Codecs

Ultravox Realtime currently supports the following codecs for SIP:

  • PCMA
  • PCMU

Using any other codec will cause calls to fail.

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Integrations