Google has been going out of its way to keep Allo relevant, but there's been one glaring issue: you need a phone number to sign up. How's it going to compete with iMessage or Facebook Messenger if there needs to be a phone involved at some point? You might not need one soon... or at least, you'll be less dependent on it. The 9to5Google crew has sifted through the code of Allo's latest Android release and discovered hidden references to chatting with Gmail contacts once you connect your account. You could find people through their email addresses once you've linked things up, too.