Back when it was TextSecure.
Also, it's worth noting that the Signal team didn't work on WhatsApp. It was WhatsApp that chose to integrate the Signal protocol, which Open Whisper Systems/The Signal Foundation open-sourced their protocol.
Also, it's worth noting that the Signal team didn't work on WhatsApp. It was WhatsApp that chose to integrate the Signal protocol, which Open Whisper Systems/The Signal Foundation open-sourced their protocol.