Voice API & SIP Trunking # Voice API & SIP. Make the right connection. Route incoming calls with sequences or connect your phone system over SIP. Keep numbers, recordings and call outcomes connected to your customer workflow. [Start now](/dashboard/signup?returnTo=%2Fdashboard%2Fw%2Fvoice%2Fonboarding) [Talk to sales](/demo?product=voice) ## Illustrative Voice experience Orders Support Studio visits BIRD / VOICE Illustrative experience Application call flow SIP connection Call records f. CALL CONNECTED · EXAMPLE Fieldnotes Studio 00:24 1 Studio visits · 2 Orders · 3 Support 1 2 ABC 3 DEF 4 GHI 5 JKL 6 MNO 7 PQRS 8 TUV 9 WXYZ ＊ 0 + # Hide Keypad Your call flow 01 Answer Your application welcomes the caller. ✓ 02 Collect a choice Keypad input: 03 Route the call team ↗ Connected to Keep your phone system SIP / EXISTING INFRASTRUCTURE Your system. A new connection. Your PBX Existing extensions & routing ↔ SIP trunk Connection to Bird Calling network Incoming & outgoing calls SIP + application trace · illustrative Example · no request is made Context for the next conversation YOUR CUSTOMER RECORD The call ends. The context stays. Customer Alex Lee Team Related visit FN–1042 Your application records the resolution and chooses any follow-up message. Example content and data. Explore the workflow below; nothing is sent or changed in a live account. ```text call_example_fn1042 10:42:00 SIP call initiated 10:42:04 Keypad choice: 1 10:42:05 Studio visits route selected 10:42:09 SIP call answered 10:44:31 Call ended Customer outcome: recorded by your application ``` Companies that trust Bird across their communications. - [Airwallex](/customers/airwallex) - Uber - [Zillow](/customers/zillow) - [Glovo](/customers/glovo) - PayPal - Adobe Voice — Incident notifications with local caller identification PagerDuty’s customer story describes Bird Voice and local numbers for incident alerts worldwide. [Read PagerDuty’s story](/customers/pagerduty) [Read call outcomes ↗](/docs/guides/voice/call-log) ## A small choice. The right team. Choose an application route and inspect an answered, busy, unanswered or unknown call. Signaling, caller audio and the business result are separate observations. CALLER / A USEFUL CHOICE FN–1042 / CUSTOMER CALL How can we help? Studio visits 1 Orders 2 Support 3 Inspect the telephone outcome Answered Busy · SIP 486 No answer Unknown final result ROUTING / CALL RECORD Incoming number → Bird SIP ↓ Inspect final record Read call outcomes ↗ Interactive illustration · fictional customer and results · no messages are sent ### answered SIP connection established Connected media path; no playback Check booking FN–1042 in the application. Answered does not prove the request was completed. ### failed · SIP 486 Destination busy No connected conversation Keep the original callback case. Apply a deliberate retry policy after checking the destination; do not call busy a completed conversation. ### no_answer Rang until timeout No connected conversation Offer the agreed alternate contact or schedule a later attempt under your application policy. ### unknown Final response unavailable Conversation outcome unconfirmed Reconcile the original call and application case before any replacement call. Unknown does not authorize a duplicate callback. WHAT IT MEANS FOR YOUR CUSTOMER ## A clear route. A person who can help. Make calling part of the customer journey. Give the caller a useful introduction, the right destination, and a follow-up they can keep. 01 / Before the call ### Start with a little context. An appointment, order, or support request gives the conversation a useful beginning. 02 / During the call ### Connect to the right place. Build prompts and routing into your application, or connect the phone system your team already uses. 03 / After the call ### Leave something useful behind. Let your application send a written confirmation or next step through Email or messaging. FIND YOUR WAY IN ## Choose the connection your team needs. Connect your existing phone system ### SIP connectivity. Your PBX or SBC owns extensions and application logic. Bird connects eligible calls after trunk admission, direction and routing are configured. [Prepare SIP setup ↗](/docs/guides/voice/sip-trunks) Build a connected application ### Application-owned calling. Connect the application through SIP. You can also publish and run Bird-native sequences from your dashboard. [Plan the application path ↗](/docs/guides/voice/call-sequences) ### The details behind your setup #### Connected application Your PBX, SBC or SIP application owns prompts, keypad choices, team routing and business actions. Bird supplies the configured voice connection. #### SIP connectivity Prepare admission, calling direction, caller identity, number binding and eligible destinations. A new trunk allows no calls and enables neither direction. #### Native call sequences Draft, validate and publish native sequence versions in your workspace, then configure the inbound route or outbound call in the dashboard. READY WHEN YOU ARE ## A calling plan you can build on. [Start now](/dashboard/signup?returnTo=%2Fdashboard%2Fw%2Fvoice%2Fonboarding) [Talk to sales](/demo?product=voice) 01 [Choose your calling owner ↗ Separate your PBX or application logic from SIP connectivity and call-record reads.](/voice#decisions) 02 [Prepare the identity ↗ Follow the setup requirements for your caller and destination.](/docs/guides/voice/first-call) 03 [Connect and inspect ↗ Use call records and events to understand the result.](/docs/guides/voice/events) BUILD WITH VOICE ## Give every call a clear direction. Route incoming calls through a published call sequence, or connect your PBX and voice agent over SIP. Follow each call through its events and final record. The examples here show the SIP test and SDK call reads. The terminal example requires the Bird CLI, baresip, an enabled trunk, a verified caller ID and an enabled destination. It places a real, billed call. Follow the setup guide before running it. [Place your first call ↗](/docs/guides/voice/first-call) [Run the terminal quickstart ↗](/docs/guides/voice/terminal-first-call) [Create session credentials ↗](/docs/cli/reference/voice-session-credentials-create) [Configure a trunk ↗](/docs/cli/reference/voice-trunks-create) [Connect a SIP client ↗](/docs/guides/voice/sip-clients) [MCP connection ↗](/ai/mcp-client) [Read the call record guide →](/docs/guides/voice/call-log) **CLI**: `Place a test call · CLI and baresip` ```bash bird voice tools test-call "$VOICE_TO" \ --trunk "$BIRD_TRUNK_ID" \ --caller-id "$BIRD_CALLER_ID" \ --protocol tls \ --duration 30s bird voice list ``` Examples: [CLI](/voice.cli.md) · [TypeScript](/voice.ts.md) · [Python](/voice.py.md) · [Go](/voice.go.md) · [PHP](/voice.php.md) · [cURL](/voice.curl.md) THE COMPLETE BIRD PLATFORM ## Let the conversation change channels. A message can become a call. A call can become a clear written follow-up. Connect the moments with Voice, WhatsApp, and Email. [Today · 9:41 Can we move booking FN–1042 to Friday afternoon? I’ll check with the studio. Your booking details are here.](/whatsapp) 01 ### [WhatsApp ↗](/whatsapp) Alex requests help with booking FN–1042. INCOMING CALL FN–1042 AL Alex Lee Studio visits · Connected to Mia A voice. A choice. A connection. Call completed 2m 31s 02 ### Voice This step Your application offers a call and routes the question to the studio. [Your studio visit. All in one place. fieldnotes. BOOKING FN–1042 Your studio visit. All in one place. Alex Lee · Friday, 14:00 Clay workshop · One guest View your booking ↗](/email) 03 ### [Email ↗](/email) Send the confirmed arrangement after the conversation. BUILD YOUR BIRD SETUP A useful next connection. [WhatsApp ↗ Keep the request in view Let the conversation continue before or after a call.](/whatsapp) [Apple Messages ↗ Help in Messages Add a supported Apple service entry point.](/apple-messages-for-business) [SMS ↗ Send the useful reminder Connect appointment updates to your calling workflow.](/products/sms) [Agent mailboxes ↗ Keep the written conversation Bring replies and follow-up into an application mailbox.](/agent-mailboxes) A phone conversation can sit beside the original email and a later SMS update. Build the handoff around the same customer, instead of treating each channel as a separate relationship. [Plan your complete Bird setup ↗](/demo?product=voice) LEARN / BUILD / OPERATE ## Go further with Voice. [FIELD GUIDE Build a phone menu that works. Create spoken prompts, keypad branches and a testable published sequence. Read the field guide →](/docs/guides/voice/call-sequences) [01 Place your first call Configure your number, place a test call and inspect the result. ↗](/docs/guides/voice/first-call) [02 Design a call sequence Prompts, input, and routing. ↗](/docs/guides/voice/call-sequences) [03 Connect SIP trunks Use your existing voice infrastructure. ↗](/docs/guides/voice/sip-trunks) [04 Follow call events Read status without confusing connection with resolution. ↗](/docs/guides/voice/events) [05 Record and review a response Capture audio, join the transcript and inspect its state. ↗](/docs/guides/voice/recordings) [06 Voice task library Find Start, Build, Diagnose, Migrate and Evaluate tasks. ↗](/voice/resources) [07 SIP trunk evaluation Prepare your PBX, network and interoperability checklist. ↗](/sip-trunking) [08 Launch readiness Check a controlled call and its independent results. ↗](/products/voice/getting-started) [09 Number identity Separate inbound capability from outbound presentation. ↗](/products/voice/numbers) [10 Incoming routing Route to a trunk, forwarding number or call sequence. ↗](/products/voice/inbound-routing) [11 Outbound callback Retain the original attempt when the result is unknown. ↗](/products/voice/outbound-calls) [Choose Voice API or SIP ↗](/guides/choose-voice-api-or-sip) Compare call-workflow responsibilities, connection requirements and recovery before choosing your architecture. VOICE / YOUR CALLING SETUP ## Choose the connection. Plan the conversation. Start with supported SIP workspace setup. Confirm number eligibility, interoperability, destinations and capacity with Bird; configure native sequences in the dashboard. [Start now](/dashboard/signup?returnTo=%2Fdashboard%2Fw%2Fvoice%2Fonboarding) [Talk to sales](/demo?product=voice) [View Voice rates ↗](/pricing/voice/us) YOUR VOICE SETUP SIP connectivity Numbers, call legs and handling have distinct charges. Calling Origin, destination, direction and number type determine rates. Rated components Number rental, call legs and handling use their own units and increments. Evaluation Confirm capacity, media compatibility and account access before rollout. ## Voice, answered. ### Is this a complete contact centre? Voice provides numbers, connectivity, and programmable building blocks. The routing, agent experience, and business workflows you need should be scoped with your implementation. ### Can I keep my existing PBX? SIP connectivity is designed to work with an existing phone system. Check compatibility, configuration, destination coverage, and capacity for your deployment. ### Should I choose the API or SIP? Use the API to start a published sequence and follow its call record. Use SIP to connect a PBX or calling application that owns the conversation. Both paths connect the telephone outcome to your customer workflow. ### Where do recording requirements belong? Decide the recording need, customer notice, access, and retention before enabling a supported recording capability. Recording is not implied by making a call. ### How do I get started or speak to sales? Start with a Bird account and follow the setup path on this page. Our sales team can help with migration, volume, or a wider product mix. Start now or talk to sales. YOUR NEXT CONNECTION ## A little more human. From the first hello. [Start now](/dashboard/signup?returnTo=%2Fdashboard%2Fw%2Fvoice%2Fonboarding) [Talk to sales](/demo?product=voice) [Explore the whole Bird platform ↗](/products) ## Related resources - [Voice overview](/docs/guides/voice/overview) (docs) - [What is a voice API?](/explained/voice/what-is-a-voice-api) (answer) [Get an implementation brief](/learn/workspace?topic=voice)