Callsign

Callsign provides identity and authentication technology that uses behavioral biometrics, device signals, and contextual data to continuously assess whether the person behind a login or transaction is who they claim to be, aiming to reduce reliance on static credentials like passwords and one-time codes that are vulnerable to phishing and account-takeover fraud. The platform is built primarily for banks and other regulated financial institutions that need to balance fraud reduction against customer friction.

Founded in 2011 and headquartered in London, Callsign raised a $35 million Series A in 2017 led by Accel with participation from PTB Ventures, Allegis Capital, and NightDragon, and later brought in strategic investment from JPMorgan and HSBC’s venture arms — a notable signal since both are also potential large enterprise customers in the identity and fraud space. The company has grown from roughly 175 employees in 2022 to between 248 and 279 by 2025, and has partnered with vendors including Microsoft, Temenos, and Intel to embed its authentication technology into banking and enterprise software stacks.

Strategic investment from two major global banks lends real credibility, but public, named case studies quantifying fraud-reduction or false-positive rates at specific customers were not found, so the practical efficacy of the platform in production is better evidenced by its bank-investor relationships than by independently published results.