Sigma AI is a global data-annotation and AI training-data company with a contributor workforce of more than 25,000 people across dozens of countries. Their recruiters were handling applicant messaging by hand across email, phone and spreadsheets, and every message had to meet EU data-protection rules. I built and run a dedicated Arino One instance for them on the WhatsApp Business Platform, powered by Infobip. It includes: a dual-number workspace (selection and production senders) automated candidate journeys from application to onboarding: confirmations, scheduling invites, reminders and stage updates a shared inbox for 20+ recruiters with assignment, handover and role-based access native Meta one-tap opt-in, an append-only consent ledger, instant keyword and button opt-out OTP-verified right-to-erasure flows with a signed completion receipt, plus a live consent health dashboard a 44-case QA test plan, signed off by Sigma AI's CTO WhatsApp is now the operational backbone of their global HR function, with compliance designed in before the first message was sent.