As reported by MacRumors, you can now register for open beta to test WhatsApp’s Multi-Device feature. Currently, it’s available for all iOS and Android users to test, with rumors that it will arrive on the iPad later on.
If you would like to test it out, just head to WhatsApp, open the Settings page -> Linked Devices -> Multi-Device Beta -> Join Beta. Once it’s activated, you can start trying out the feature, but if anytime you would like to leave the open beta, you just have to go back to the same settings and there should be an option to leave.
If you weren’t aware, this feature allows you to link your devices and let you receive messages without needing your phone to be online. It works when you connect to the WhatsApp desktop app or through any web-based service, which then allows you to start messaging.
It however does not work if your software is outdated on your device, and it is only available on one WhatsApp account at a time. So you won’t be able to receive or send messages if it does not meet the requirements.
Additionally, if your phone is inactive for 14 days or longer, your linked devices will be automatically disconnected. The feature might also have a lot of issues since it is still in beta, so be aware before joining the beta.