Google Allo works with SMS and even when not installed

Google’s new messaging app Allo takes a unique and interesting approach to get new users on board: it sends notifications to Android users and even allows them to type a response. For non-Android users, a text message is sent with an invitation to install the app.

Whether or not this behavior is clear to users — and doesn’t rub off a spammy/malware vibe — it is very interesting from a technical perspective. Let’s take a closer look.

Chatting without Allo installed (Android only)

Receiving a message on an Android device without Allo installed

Google informs you of what’s going on when you receive your first Allo message by showing a bit pop up card with a link to more information. The emphasis is on installing the app, but you don’t have to; you can simply respond to the message.

Typing a reply from the notification

This notification is part of Google Play Services, an app by Google that is silently kept up to date on virtually all Android devices that provides a magnitude of features, from push notifications to high-fidelity and low-power location updates.

The notification sticks around so you can keep sending messages.

You are constantly pestered to install the app

Messages are sent and received through these push notifications only if your device is connected to Google Play Services. If Google can’t deliver the message to you via push, they’ll fall back to sending a text instead, much like Apple’s iMessage.

Chatting through SMS without Allo installed

Not all features are supported without the app, such as stickers

If you have an iPhone without Allo, or if your Android device doesn’t sport Google Play Services, you will receive text messages. And because they’re relayed through Google’s free SMS service, it’s free.

Again, the first message explains what’s going on:

Chatting goes over SMS when Allo is not installed

Paul added you on Google Allo to chat. Text HELP to learn more or STOP to unsubscribe.

You’re provided a link to read more about Allo, and immediately the message arrives as a conventional text message. Replying to it is again free of charge, and the recipient will see that message come in natively inside the Allo app on his phone.

Thanks to Reddit user theturbanator1699 for testing on Google Voice and providing a screenshot of SMS behavior.