Phone numbers, voice,
and SMS as an API
Provision numbers, stream real-time audio, route SMS. One API, carrier-grade reliability. No platform fees, no contracts.
Get a number, configure where audio goes, start receiving calls. Kadeno handles SIP, RTP, and carrier routing.
Get a phone number
Search by area code. Purchase instantly. Number is live in seconds.
{ "area_code": "212" }
Set your endpoint
Tell Kadeno where to send audio and SMS. WebSocket, HTTP, or SIP — your choice.
{ "voice_url": "wss://..." }
Handle calls and messages
Kadeno streams audio in real time and forwards SMS to your endpoint. You process, we relay.
// at 8kHz. Process however you want.
Kadeno is telephony infrastructure. What you build on it is up to you.
AI Voice Agents
Give your AI agent a real phone number. Kadeno streams call audio to your AI endpoint and relays responses back to the caller in real time.
VoIP Applications
Build consumer or business calling apps. Kadeno provides the carrier connectivity, you build the experience. Inbound and outbound.
SMS & Verification
Send and receive SMS. Use Kadeno numbers for 2FA, notifications, customer support, or conversational messaging.
Call Analytics & Recording
Intercept and analyze call audio for quality monitoring, compliance, sentiment analysis, or transcription pipelines.
not months
One API key. RESTful endpoints. Real-time audio over WebSocket. Kadeno handles the SIP stack, carrier negotiation, and number management.
- ✓ Provision numbers via REST API
- ✓ Real-time audio streaming (WebSocket or SIP)
- ✓ Inbound and outbound SMS
- ✓ Per-resource usage metering
- ✓ Webhooks for call events and delivery status
- ✓ Multi-carrier routing (automatic failover)
# Search for a number curl https://api.kadenotec.com/v1/numbers/search \ -H "Authorization: Bearer kd_live_..." \ -d '{ "area_code": "415" }' # Purchase it curl -X POST .../v1/numbers/purchase \ -d '{ "number": "+14155550123" }' # Configure voice endpoint curl -X PATCH .../v1/numbers/+14155550123 \ -d '{ "voice_url": "wss://your-app.com/voice", "sms_url": "https://your-app.com/sms" }' # Done. Calls and SMS are now routed # to your endpoints.
No platform fees. No subscriptions. No minimums. Pay for exactly what you use, billed monthly.
| Service | Kadeno | Twilio | Telnyx |
|---|---|---|---|
| Inbound voice | $0.007/min | $0.0085/min | $0.0075/min |
| Outbound voice | $0.009/min | $0.014/min | $0.009/min |
| Local number | $1.00/mo | $1.15/mo | $1.00/mo |
| Toll-free number | $1.15/mo | $2.15/mo | $1.00/mo |
| SMS outbound | $0.008/msg | $0.0083/msg | $0.004/msg |
| SMS inbound | $0.003/msg | $0.0083/msg | $0.003/msg |
| Platform fee | $0 | $0 | $0 |
US rates shown. Card required at signup. Usage billed monthly. Volume discounts available.
- $8.50 voice
- $1.15 number
- $7.00 voice
- $1.00 number
- $7.50 voice
- $1.00 number
Build on Kadeno
Create an account. Get an API key. Provision your first number.
Pay-as-you-go. No contracts. No minimums.
Voice API — Programmable voice with real-time audio streaming. Make and receive phone calls via SIP trunking or WebSocket. G.711 and PCM audio codec support. Sub-200ms latency on US routes.
Phone Number Provisioning — Search and purchase local and toll-free US phone numbers via REST API. Instant activation. Numbers assignable to endpoints, agents, or applications.
SMS & MMS — Send and receive text messages programmatically. Delivery status webhooks. 10DLC campaign support for A2P messaging. Inbound SMS forwarding to any HTTP endpoint.
Real-Time Audio Streaming — Bidirectional audio over WebSocket for voice AI, call transcription, sentiment analysis, and live audio processing. Connect any speech-to-text or text-to-speech engine.
SIP Trunking — Enterprise-grade SIP connectivity with IP-based authentication. Bring your own PBX, softphone, or SIP client. Compatible with FreeSWITCH, Asterisk, and any SIP-compliant system.
Call Control — Programmatic call management via REST API. Initiate outbound calls, transfer calls, play audio, gather DTMF input, and record calls.
Multi-Carrier Routing — Automatic failover across redundant carrier paths. Geographic routing optimization. Carrier-grade reliability with 99.95% uptime SLA.
Webhooks & Events — Real-time event notifications for call state changes, SMS delivery, and number status. Configurable per-number webhook endpoints with HMAC signature verification.
Usage Metering — Per-resource usage tracking and billing via Stripe integration. Track minutes, messages, and active numbers. Build your own billing on top with custom markup.
AI-Ready Infrastructure — Purpose-built for AI voice agents, conversational AI, and intelligent call routing. Connect to any AI engine — OpenAI, Anthropic, custom models, or our default CAIZA engine. Kadeno handles telephony, you handle intelligence.