At Google I/O 2016, Google announced two new messaging products: Allo, for text messaging, and Duo, for video communications. These are the most recent in a series of messaging products Google has created, none of which have succeeded in attracting a really large user community the way that other messaging products have done. Google doesn't release figures for monthly active users of Hangouts, while WhatsApp has a billion users, Facebook Messenger and QQ have 850 million, and WeChat has about 700 million. The stakes in messaging are very high, and, so far, Google is an also-ran.
In 2015, it looked like Google might go in a different direction, perhaps acting as a spoiler for proprietary messaging apps that don't interoperate and don't use carrier protocols like SMS and MMS. Google bought a company called Jibe that makes next-generation messaging servers for standard telecom protocols called Rich Communications Services, or RCS. If Google based a messaging system on RCS it would be inherently open and would interoperate with any client or server implementing a compatible RCS profile. Standards and interoperation could be a shortcut to wider use.
Are Allo and Duo the first shots fired in that battle? The short answer is "No." It looks like Allo and Duo have nothing to do with Jibe RCS, or RCS in general. Instead they are aimed at providing a better messaging experience, providing messaging privacy, and providing decent performance in challenging network conditions. Duo uses QUIC, a protocol that combines all the things, like throttling and encryption, that one has to build on top of UDP to do efficient and secure multimedia communications on wireless IP networks. Duo's claimed advantage is better performance in conditions where other video messaging apps could become unusable. But the signaling to set up tDuo video calls is WebRTC, not RCS. The protocol used to move video call payload is QUIC.
Here is some information on QUIC: https://www.chromium.org/quic
End users may be getting whiplash from Google's changes of direction, and the tactical approach they are taking with a product for each kind of partnership or competitor.
Moreover RCS messaging gets viewed askance because carriers are required to provide lawful intercept (LI) capability - a built-in law enforcement back door - for their messaging as well as for calls. Therefore, if Google provides RCS signaling and messaging for a carrier, or if Project Fi is a carrier, they would also have to provide LI for RCS-based messaging. Users of messaging apps that go "over the top" (OTT) of carrier networks are increasingly aware of security and are choosing more-secure apps like Whatsapp and Telegram.
To provide a high quality response to increased security awareness, Google is using Open Whisper Systems's (OWS) encryption for a secure mode in Allo,and the QUIC protocol stack has end to end encryption built in for real-time communication. OWS makes open source encryption products that have a first tier reputation among security experts. Allo and Duo should have some of the best security for communication available.
Despite all the confusion Google has managed to create, the technologies behind these products, especially QUIC, are still of interest, and it remains possible that OWS end-to-end encryption could end up in Google's as yet unannounced RCS-based products.