Bird vs Vapi for Voice
Bird provides phone numbers, SIP trunks, versioned IVR call sequences, and cross-channel messaging logs. Vapi provides an AI voice agent orchestration layer that connects speech models, LLMs, and tools over SIP, so teams can use them together or evaluate which layer they need.
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How Bird and Vapi fit into your voice architecture
Compare how each platform handles AI agent orchestration, SIP trunk connectivity, and backend tool actions.
| Capability | Bird | Vapi |
|---|---|---|
| AI conversation orchestration | Bridge phone calls over SIP to the AI voice runtime that runs your speech model, prompts, and tools. | Configure voice assistants, transcribers, models, voices, and custom tools in Vapi. |
| SIP connection | Provide local phone numbers and authenticated inbound and outbound SIP trunks for your PBX or AI runtime. | Connect assistants to external telephony providers through Vapi's SIP trunking integration. |
| Business actions | Trigger webhook steps from IVR sequences, transfer callers over SIP, and send follow-up SMS, WhatsApp, or email messages. | Call backend APIs during a live conversation using Vapi's built-in and custom assistant tools. |
When is Vapi a strong choice?
Vapi fits teams that want a managed orchestration layer to wire together speech-to-text, LLM prompts, text-to-speech, and tool calls without building the realtime voice loop themselves.
When should you choose Bird?
Choose Bird when you need phone numbers, authenticated SIP trunks, and versioned IVR call sequences in the same workspace as your SMS, WhatsApp, and email channels, whether you run your own voice agent server or bridge calls to an external assistant runtime.
Could I use Bird and Vapi together?
Yes. Because Bird provides carrier phone numbers and SIP trunks while Vapi orchestrates the AI assistant over SIP, you can use Bird as the telephony carrier for a Vapi assistant. Configure a Bird SIP trunk, point inbound and outbound routes between Bird and Vapi, and test caller ID, two-way audio, and call transfers on a pilot number.
How should you compare the full cost?
Price the complete call using your real destination countries, inbound and outbound call mix, and average call length. A carrier SIP rate covers phone network transport, while an assistant orchestration rate covers or passes through speech recognition, LLM inference, and voice synthesis. Add telephony, number rental, and AI runtime costs together when comparing options.
What does a careful migration involve?
Decide first whether you are moving only your phone numbers and SIP carrier connection to Bird while keeping Vapi for assistant orchestration, or replacing the assistant runtime as well.
Separate telephony from assistant logic
If you are keeping Vapi for dialogue, configure a Bird SIP trunk to carry the phone calls. If you are moving to your own voice agent runtime, rebuild your prompts, tool webhooks, and transfer rules in that runtime and use Bird call sequences for fixed IVR steps.
Test a complete call end to end
Assign a test number in Bird and run real inbound and outbound conversations to verify audio latency, caller barge-in, keypad input, tool execution, and call detail records before changing production routes.
Port numbers and cut over traffic
Confirm number portability for each country, bind ported or newly provisioned numbers to your verified Bird SIP trunk or call sequence, and shift live traffic in stages.
Questions about Bird and Vapi
Could I use Bird and Vapi together?
Can I keep my current phone numbers?
How should I evaluate call quality?
Should I start self-serve or talk to a Voice specialist?
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Primary documentation
Related resources
Continue with the documentation, guides and examples for this topic.
Talk to our Voice team
Plan your Vapi integration or migration.
Review your phone numbers, SIP trunk configuration, and AI voice runtime with our team, and validate a complete call flow on Bird before moving production traffic.