For developers
Voice API, SIP trunk, Number API and webhooks: build on the same Korean lines we run. API documentation on request.
Platform
KAT runs the telecom layer under its own licences and builds AI, messaging, payments and data on top. Everything below runs on that one stack.
We operate the telecom layer ourselves. Where we rely on partners for a piece of a layer, we say so.
L5Data
Recordings & summaries · Dashboards & analytics · API & webhooks · Slack, Jandi, Notion, Google
Run by KAT
L4Payments
In-call payment, without hanging up
BetaAvailable inside ZeroCall
L3Messaging
SMS · LMS · MMS · KakaoTalk business messages · KakaoTalk support chat
Run by KAT, delivered through messaging partners
L2AI
Speech-to-text · LLM dialogue · Real-time TTS · Industry task modules
Pipeline orchestrated by KAT. Speech recognition and language models come from cloud AI providers.
L1Telecom
Two telecom licences · Number issuance & porting · SIP switch · Routing, IVR & queues · SIP trunking
Operated by KAT. Calls to other networks pass through standard interconnection with partner carriers.
KAT is a registered Korean telecom carrier. We issue business numbers and run our own SIP switch, and the two licences together cover the line and the AI on top of it.
Registration No. 1-01-25-0027
Lets us issue phone numbers and provide voice transmission ourselves.
Registration No. 3-01-25-0010
Covers AI answering, recording, transcription and messaging under one operator.
070 business numbers
Main lines and per-staff direct lines
Live in about a minute
Local numbers02, 031 and more
A local presence for stores and offices
National numbers15xx · 16xx · 18xx
One memorable number for the whole business
Calls to and from other networks pass through standard interconnection with partner carriers. Existing numbers can be ported in.
It hears, decides, speaks and acts on real calls, through line noise and dropouts. If one step lags, the conversation breaks, so each part is tuned for live phone audio.
Transcribes speech through line noise and dropouts.
Remembers what was said and decides what to say and do next.
Answers in a natural voice, fast enough to keep the conversation going.
Booking, intake and notices, handled the way each industry needs.
Recording
Transcript & summary
AI voice agent inbound & outbound
Voice selection & custom voices
KAT orchestrates the pipeline on AWS. Speech recognition and language models come from cloud AI providers under contract, including transfer outside Korea.
AI agent contact center integrated with booking platforms
Korean Patent No. 10-3022994 (2026)
What the infrastructure does today, with a status on every item.
Status as of October 2026.
Keep your PBX, your desk phones and your tools. KAT adds Korean lines and an AI agent on top, over standard SIP.
Answer and make calls from phone or desktop through ZeroCall, on the same number.
Standard SIP desk phones register to our switch. Send us the model and we’ll confirm.
Keep your exchange and add our lines and AI. Avaya Aura is a compatible environment, over SIP trunk and VPN.
Other SIP-compatible PBXs: ask us and we’ll confirm the setup.
Voice API, SIP trunk, Number API and webhooks: build on the same Korean lines we run. API documentation on request.
Slack
LiveCall alerts in your channels
Jandi
LiveCall alerts for teams on Jandi
Notion
LiveCall records in your workspace
Call records in Google
CRM
Coming soonCustomer records built from call history
Tell us what you’re building and what you run today, and we’ll suggest a setup that fits.