 Koum changed WhatsApp to "ping" users when they received a message, and soon afterwards he and Fishman's Russian friends in the area began to use WhatsApp as a messaging tool, in place of SMS.The app gained a large user base, and Koum convinced Acton, who was then still unemployed, to join the company.Koum granted Acton co-founder status after Acton managed to bring in $250,000 in seed funding.