Cantoo

Communication service providers wanted to sell voice, SMS, and phone numbers under their own brand without building and operating telecom infrastructure themselves.

Cantoo offered that as white-label, API-driven hosted services. It had to carry industrial-scale voice and messaging traffic with carrier-grade reliability, comply with telecom regulation in several countries, and do it without venture funding.

• I designed and built the full technical stack from zero, starting with a cloud-native, distributed voice infrastructure on Kubernetes with auto-scaling and auto-healing.
• I built a real-time routing engine that picks routes by cost, quality, and latency, and deprioritises a carrier as soon as it starts returning errors.
• I built a real-time billing pipeline on ClickHouse and Pulsar for instant usage tracking across voice, SMS, and DID.
• I built the white-label, API-driven services (voice, SMS, DID) that operators integrated into their own products, and took Cantoo through registration as a telecom operator in the UK, France, and Germany.
• I built and led a remote engineering team with a 24/7 on-call rotation, and after the acquisition I led the technical integration into 42com.

• Multi-dimensional routing instead of cheapest-route

  Why: margins were thin and a dip in quality or latency could lose an operator for good

  Cost: it became the component everything else depended on, so getting it wrong would have meant rewriting everything.

• PostgreSQL for everything first, ClickHouse for analytics only once query times hurt

  Why: no second database to run early on

  Cost: it worked because the data model was designed for that split, and the migration took weeks, not months.

• Kubernetes from the start

  Why: carrier-grade reliability later on

  Cost: for the first six months it cost weeks of setup a two-person team did not need yet; a few VMs would have done.

Cantoo became profitable in under two years and reached €400k/year in revenue without a funding round. It operated as a registered telecom operator in the UK, France, and Germany. In Q4 2023 it was acquired by 42com, a wholesale telecom provider, and because the systems were modular and documented, the integration took months, not years.

Kubernetes · Go · TypeScript · Vue/Nuxt · Kamailio · FreeSWITCH · PostgreSQL · ClickHouse · Redis · Pulsar · Terraform · GCP/AWS · GitLab CI

Cantoo proved that you don't need venture capital to build something real. Constraints forced us to focus: we shipped faster, spent less, and reached profitability by saying no to features that didn't directly generate revenue.