TECH CRUNCH - WhatsApp is rolling out multi-device login support that allows users to log into the same account on up to four phones. The new feature will sync messages across devices, even if one device is switched off, and comes with new technology to maintain end-to-end encryption protection. The company is also introducing a one-time code for linking devices instead of scanning a QR code on a mobile phone. The feature will be available to all users in the coming weeks.