In June 2009, Apple launched push notifications, allowing users to be pinged when they were not using an app.
Koum changed Whats App so that when a user's status is changed, everyone in the user's network would be notified.
Whats App was switched from a free to paid service to avoid growing too fast, mainly because the primary cost was sending verification texts to users.
In December 2009, the ability to send photos was added to Whats App for the i Phone. In April 2011, Sequoia Capital was the only venture investor in Whats App and paid approximately $8 million for more than 15 percent of the company, after months of negotiation with Sequoia partner Jim Goetz.
A month later support for Windows Phone was added, followed by Black Berry 10 in March 2013.