Key facts
- Offices: Callsign's registered office is at 138 Cheapside, London EC2V 6BJ.
- Capital: Accel and PTB Ventures led Callsign's US$35 million Series A in July 2017, with Allegis Capital and NightDragon taking part.
- Leadership: Founder Zia Hayat leads the company as chief executive and serves on the board alongside directors Garth William Ritchie and Stephen John Dempsey.
- Standards: Callsign joined the FIDO Alliance as a sponsor member in July 2026.
Focus areas
About
Callsign is a London digital identity and authentication company. Its platform combines an Intelligence Engine, an authentication suite and an orchestration layer, so banks and other businesses can recognise genuine users and step up checks only when risk rises. Use cases include account takeover, KYC and AML onboarding, PSD2 strong customer authentication, SIM swap, scams, synthetic identity, zero-trust network access and iGaming. Zia Hayat founded Callsign in 2012 and leads it as chief executive. The company joined the FIDO Alliance as a sponsor member in July 2026.
How they use AI
Callsign's Intelligence Engine applies machine learning to behavioural biometrics such as typing, swiping and mouse movement, alongside device fingerprinting, location and telco intelligence, to judge whether the person behind a session is the genuine user. The engine scores each interaction in real time, and the orchestration layer uses that score to decide whether to let a user through, add a challenge or block the session. Callsign One brings passwordless and multi-factor authentication methods into the same flow, so step-up checks appear only when the risk score calls for them.
Products and services
- Intelligence Engine — Machine-learning risk engine using behavioural biometrics, device fingerprinting and telco intelligence
- Callsign One — Authentication suite with passwordless and multi-factor methods driven by risk scores
- Orchestration Layer — Policy layer that routes users to allow, challenge or block decisions across journeys
- Fraud and identity solutions — Account takeover, KYC/AML, PSD2 SCA, SIM swap, scam, synthetic ID, ZTNA and iGaming use cases
Key people
- Zia Hayat — Founder and Chief Executive Officer
Investors
- Accel
- PTB Ventures
- Allegis Capital
- NightDragon
