One API call buys your agent a real US number. Calls arrive as a two-way audio stream your agent can listen to and speak into, or as SIP to the voice stack you already run. Dialing out unlocks once a human has verified who's behind the account.
Runs on the same carrier network we operate for military, maritime and enterprise customers. Part of the NT Connect platform.
sc = httpx.Client(base_url="https://sipcraft.dev", headers={"authorization": f"Bearer {API_KEY}"}) # give your agent a number of its own num = sc.get("/v0/numbers/search", params={"area_code": "415"}).json()["numbers"][0] sc.post("/v0/numbers", json={"e164": num["e164"], "confirm": True}) # calls stream to your agent over a WebSocket sc.patch(f"/v0/numbers/{num['e164']}", json={ "route_type": "websocket", "route_target": "wss://agent.example.com/media"})
SIPCraft is the telephony layer underneath your agent. It isn't a voice-agent builder. Bring any model and any framework; we handle the numbers, the signalling, the audio and the paperwork.
Search by area code or state and buy with confirm: true. Your first number is free. Inbound is live the moment the purchase returns.
Route calls to a wss:// media stream (G.711 µ-law, 8 kHz, 20 ms frames), a SIP URI on LiveKit, Pipecat or your own PBX, or a CallCraft agent.
Calling phone numbers needs a one-time Get Verified check powered by Didit (ID, liveness and AML; KYB for businesses) and a consent attestation on every call.
A remote MCP server (Streamable HTTP) with 30 tools. Anything that spends money takes an
explicit confirm: true. Tools that dial phone numbers refuse until you Get Verified, and they say why.
Responses are short JSON, not dumps.
{
"mcpServers": {
"sipcraft": {
"url": "https://sipcraft.dev/mcp",
"headers": { "Authorization": "Bearer sk_..." }
}
}
}
# read account_overview get_usage get_compliance_status search_numbers list_numbers list_calls get_call get_recording_url list_events get_verification_status # write (purchases need confirm:true) buy_number release_number configure_number set_cnam set_e911_address create_sip_trunk set_webhook test_webhook get_verified # on-net, free: no number, no verification create_endpoint list_endpoints call_endpoint # live calls (phone numbers need Get Verified + consent) place_call hangup_call transfer_call send_dtmf start_recording stop_recording
REST under /v0 with RFC 9457 problem responses, Idempotency-Key on every write,
and scoped API keys. The OpenAPI document is published at /openapi.json.
GET /v0/numbers/search?area_code= POST /v0/numbers PATCH /v0/numbers/{id} PUT /v0/numbers/{id}/e911 POST /v0/calls POST /v0/calls/{id}/hangup|transfer|dtmf POST /v0/calls/{id}/recording/start|stop GET /v0/calls/{id} GET /v0/events?since= POST /v0/webhooks POST /v0/verification # Get Verified POST /mcp
curl https://sipcraft.dev/v0/calls \ -H "Authorization: Bearer $SIPCRAFT_KEY" \ -H "Idempotency-Key: 6f1c…" \ -d '{ "from": "+14155550123", "to": "+12125550199", "stream_url": "wss://agent.example.com/media", "consent_attestation": { "has_consent": true, "basis": "prior_express_consent" } }' # 201 {"id":"call_…","status":"in_progress"} # webhook: SIPCraft-Signature: t=…,v1=HMAC-SHA256
The control plane runs on Cloudflare's edge. Signalling and media run on NT's carrier-grade SIP core, with a media bridge that turns each call's audio into a WebSocket your agent can hold.
PSTN caller ──▶ inbound DID carrier ──SIP──▶ NT SIP core (routing, per-tenant CPS/concurrency) │ route lookup ◀─────────────┤──▶ RTP relay ──RTP──▶ media bridge (SIPCraft API) │ wss:// µ-law 8k, 20 ms, mark/clear ▼ your agent Your agent ──POST /v0/calls──▶ SIPCraft ── verified? consent? cap? ──▶ NT SIP core ──▶ outbound carrier │ STIR/SHAKEN signed CDR ──▶ queue ──▶ rating ──▶ usage ──▶ prepaid credit ledger └──▶ webhook signed · event log GET /v0/events
An AI that can dial phones is a robocall risk until proven otherwise. These controls are on by default and agents can't switch them off.
Hosted verification powered by Didit: government ID, liveness and AML screening for individuals; KYB plus signer ID for businesses. outbound_enabled stays false until it passes. NT staff review edge cases.
Each outbound call carries a consent attestation (basis and timestamp), stored with the CDR. The FCC treats AI-generated voices as "artificial" under the TCPA, so prior express consent applies.
New accounts get 100 outbound calls a day, low concurrency and a $25 monthly spend cap. Premium-rate and international destinations are blocked. Short-call and failure spikes are flagged for review.
Outbound calls from verified accounts are signed under STIR/SHAKEN by NT Connect as the originating provider. We answer industry tracebacks.
Register a service address on any number that will place calls ($1/mo). Calls to 911 route to the PSAP for that address.
Recording is off until your agent asks for it. In two-party-consent states your agent must say so on the call, and the docs show you how.
An agent minute is the carrier leg plus the audio stream to your agent, inbound or outbound, rated in 6-second increments. You bring the model. No platform fee and no seat fee. Calls between SIPCraft addresses are free. Usage is pay-as-you-go, drawn from prepaid credit: buy a credit pack, and minutes and number fees come out of your balance.
Top up in fixed packs; credit never expires while your account is open. Monthly number fees come out of the same balance. Turn on auto top-up to buy a pack when your balance drops below a threshold. Outbound stops at $0 by default so you can't overspend. Payments coming soon
| SIPCraft | Twilio | Telnyx | Vapi | |
|---|---|---|---|---|
| What you get | Number + carrier leg + audio stream to your agent | Programmable Voice (carrier leg only) | Elastic SIP (carrier leg only) | Hosted voice-agent platform |
| Per minute (US) | $0.026 in or out | $0.014 out · $0.0085 in1 | $0.005 out · $0.0032 in2 | $0.05 platform fee, before telephony, STT, LLM and TTS3 |
| Local number | $1.00/mo, first one free | $1.15/mo1 | $1.00/mo2 | Via the telephony provider you connect3 |
Competitor prices are list prices from public pricing pages as of November 2026 and don't include taxes or fees. The products aren't identical: Twilio and Telnyx charge for the carrier leg and leave the agent bridge to you, and Vapi charges its fee on top of the providers you pick. 1 twilio.com/en-us/voice/pricing/us · 2 telnyx.com/pricing/elastic-sip · 3 vapi.ai/pricing. SIPCraft is pre-launch and prices may change before general availability.
SIPCraft is the raw telephony layer. CallCraft is the finished voice agent built on top of it. They share one account and one bill through Prism.
Ready-made voice agents on real phone numbers: receptionist, scheduler, survey and order taking. Route a SIPCraft number to a CallCraft agent with one call.
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