Bird vs Retell AI for AI voice calling

Choose the parts of the calling stack you want to own: telephone connectivity, the conversation runtime and the business tools. These products can work together when the SIP integration fits.

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Where Retell AI fits

Retell provides a conversational agent runtime and documents custom telephony connections. Its agent and the telephone carrier can remain separate parts of the same deployment.

Read Retell AI documentation ↗

Where Bird fits

Bird provides the calling connection, SIP trunk configuration, number routing and call records. Connect a SIP-capable agent runtime and keep business actions tied to their actual application result.

Explore Bird Voice AI ↗

Compare the integration you will operate

Capability	Bird	Retell AI
Telephone connection	Configure the Bird trunk and route the incoming number.	Connect the runtime through its documented telephony integration.
Conversation runtime	Bring the SIP-capable runtime that handles speech, reasoning and tools.	Use the vendor’s agent runtime and its conversation configuration.
Human handoff	Test the receiving route and correlate its call records.	Configure the agent’s transfer behavior and verify it over the actual call path.

Run the same customer journey

Call the same appointment assistant with both a straightforward request and an interrupted response. Measure call setup, audio quality, tool completion and a real transfer to a person. Separate carrier costs from runtime and model costs.

Start the working example ↗

Make the switch deliberately

Move the telephone connection separately from the agent when keeping the existing runtime. Rebuild prompts and tools only if you are also changing the runtime; a SIP connection is not a replacement for the agent itself.

Migrate from Retell AI ↗

Prove the connection before moving the agent.

Test one real call through the Bird trunk, then connect the retained runtime. This verifies the telephone path; it does not migrate prompts, tools or agent state. Follow the quickstart to prepare your sender, destination and credentials.

Run the Voice quickstart ↗

test-call.sh

bird voice tools test-call "$VOICE_TO" \
  --trunk "$BIRD_TRUNK_ID" \
  --caller-id "$BIRD_CALLER_ID" \
  --protocol tls \
  --duration 30s

bird voice list

Questions before switching

Does changing telephony replace the AI agent?

No. The telephone connection and the conversational runtime are separate parts. You can retain a SIP-capable runtime while moving its telephone connection, provided the integration works for the required call paths.

What should an AI call test include?

Test incoming and outgoing calls, audio in both directions, interruption, a business tool and human handoff. Join the runtime session to the call and business records.

How should I compare costs?

Separate number rental and call-leg charges from speech, model and runtime costs. Measure the complete conversation and transfer path instead of comparing one headline per-minute rate.

Choose your next step

Migration guideMap the current integration, test the receiving path and plan the traffic transition.Voice AI resourcesFind quickstarts, implementation guides and troubleshooting.Compare other optionsReview the alternatives against the customer workflow you need.Review Bird pricingCheck the published plan or rates for the workload you are comparing.

Test it with your own workflow.

Start with the guide, or bring your integration and migration requirements to our team.