Even before Hangouts, Duo, and Allo, it was Google Talk that ruled the voice game. Then more advanced apps arrived and replaced Google Talk by offering much better features. But Google Talk was originally a desktop application and even allowed users to send messages to users on other XMPP-powered services. Google talk was updated in 2013 with Google’s Hangouts.
Recently the company has announced a complete shutdown of Google Talk. People using it right now will be invited to join Google Hangouts but after June 26th they will have to leave it for good. Even the Android App will stop functioning; therefore, users are being encouraged to switch to Google’s Hangouts. But Hangouts itself is going through a lot right now, the company is positioning Hangouts as a business centric service and is separating it into Chat and Meet. Allo and Duo are considered preferable messaging services for users but Allo still lacks the web version of it. for consumers, Google is following a pretty simple strategy i.e Allo/Duo are to be directed towards consumers, enterprises will prefer the Hangouts Chat/Meet and for carriers, there will be Android Messages. This shift will leave much to be desired.
Also, after fusing Hangouts and SMS, the company is now focusing on its Android Messages for retrieving text messages. Therefore users currently using the classic Hangouts app as their SMS client, the company will push for switching to Android Messages. Beyond Google Talk, the company is also aiming to retire few of the prominent features in Gmail such as Google+Circles as well the ability to email Google+Profiles. Google will be removing these two legacy+ features completely after April 24th.
Via: Tech Crunch