# Callsign funding: rounds and investors > Callsign has raised $109M across 2 rounds since 2017. Investors include Accel, NightDragon and PTB Ventures/ Allegis. Every round with its source. Source: https://millionrounds.com/company/callsign (Millionrounds; every figure on the page links to its filing or article) United Kingdom · [Series A startup](https://millionrounds.com/companies) # Who invested in *Callsign* 2 rounds we have observed, with the 3 investors named in them. Every figure came from a named source, and where the company reported a raise to the SEC itself, that is shown beside it. Cybersecurity Funding summary Updated 26 Oct 2026 **$109M** raised across 2 rounds since 2017, from 2 sources **$35M** Series A **$74M** Round - **Latest round:** Round, $74M Jun 2023 - **Step-up i:** 2.1× - **Investors:** 3 (1 led) See who backed them ## The funding story Each circle is a round, placed by date and sized by amount. The line above is the running total. 2018 2019 2020 2021 2022 2023 **$35M** Series A **$74M** Round - **First round:** Series A, $35M - **Biggest round:** $74M - **Between rounds:** 5.9 years ## The rounds - **Jun 2023** Round **$74M** No investor was named in the report. Shares issued, filed with Companies House (SH01); no report of this raise yet - **Jul 2017** Series A **$35M** *3 new* [Accel](https://millionrounds.com/fund/accel) Lead [NightDragon](https://millionrounds.com/fund/nightdragon) PTB Ventures/ Allegis Reported by TechCrunch ## Funding filed with regulators Callsign filed one raise, $74M in all. Filings say how much was sold and to how many investors; they never name the investors. - Jun 2023 **$74M** UK share allotment ## Who was in which round The busiest backers across the latest rounds. A filled square is a round they joined; a dark one, a round they led. **Series A** 2017 **Round** 2023 [Accel](https://millionrounds.com/fund/accel) L [NightDragon](https://millionrounds.com/fund/nightdragon) PTB Ventures/ Allegis ## Everyone who backed them [Accel](https://millionrounds.com/fund/accel) VC firm **1** round, led 1 [NightDragon](https://millionrounds.com/fund/nightdragon) VC firm **1** round PTB Ventures/ Allegis no record of our own yet **1** round Missing a round, or an investor who was in one? [Tell us](https://millionrounds.com/corrections?slug=callsign). ## Also claim to have backed them These 7 firms list Callsign as a portfolio company on their own websites, but no report of a round names them. They are the firms' own claims, kept apart from the rounds above. [Prosperity7 Ventures](https://millionrounds.com/fund/prosperity7-ventures) Corporate VC Per its own site [Sand Hill East](https://millionrounds.com/fund/sand-hill-east) VC firm Per its own site [SC Ventures](https://millionrounds.com/fund/sc-ventures-by-standard-chartered) Corporate VC Per its own site [PTB Ventures](https://millionrounds.com/fund/ptb-ventures) VC firm Per its own site [QBN Capital](https://millionrounds.com/fund/qbn-capital) VC firm Per its own site [Nautilus Investmen...](https://millionrounds.com/fund/nautilus-investmen) VC firm Per its own site [Security Leadership Capital](https://millionrounds.com/fund/security-leadership-capital) VC firm Per its own site ## Quick answers about Callsign ### Who invested in Callsign? Callsign's investors include Accel, NightDragon and PTB Ventures/ Allegis. ### How much has Callsign raised? Callsign has raised $109M across 2 rounds since 2017. ### When did Callsign last raise? Callsign's most recent round, $74M, was in Jun 2023. ### What was Callsign's biggest round? Its most recent round, $74M in Jun 2023, is also its largest on record. ### Who backed Callsign first? Callsign's first round on record, in Jul 2017, was backed by Accel, NightDragon and PTB Ventures/ Allegis. ### What stage is Callsign at? Callsign's latest named round is a Series A, in Jul 2017. ### Where is Callsign based? Callsign is based in the United Kingdom. ### Who led Callsign's rounds? Accel led the Series A in 2017. ## Companies like Callsign In the same sector, and raised in the last eighteen months. [**Blackwall** $162M · Oct 2026](https://millionrounds.com/company/blackwall)[**SafeToNet** $23M · Sept 2026](https://millionrounds.com/company/safetonet)[**OneClickComply** $2.1M · Sept 2026](https://millionrounds.com/company/oneclickcomply)[**Outerlimit** $16M · Sept 2026](https://millionrounds.com/company/outerlimit)[**SCI Semiconductor** $13M · Sept 2026](https://millionrounds.com/company/sci-semiconductor)[**Iothic** $4.7M · Sept 2026](https://millionrounds.com/company/iothic) ## Find investors like these Search every investor by what they have actually funded, then narrow to your stage and market. Free. Open the investor searchOr these rounds in the app