I think it was back in 2013 mobile communication had peaked. In one app (hangouts) I could: sms/mms/IM/phone-call/video-call using my phone, laptop, or some library kiosk browser in private mode. All of this and the notifications went to all of my devices whether or not my physical phone was powered on or connected. On my actual phone Hangouts would also show all of my local messages and I could merge conversations. Voicemails autotranscribed and you could even have them sent as emails to you. SPAM call filtering was built in. IMs could send images/videos. About the only thing it didn't do was send files (had to put it on Google Drive and share the link manually).
Now 6 years later there is nobody else (free or paid) that offers what Google offered for free in 2013. Google itself has disabled functionality in Hangouts and put out a deprecation notice. The replacement options have been spread across multiple individual app attempts, some of which have already closed down, none of which actually got to the point of replicating the functionality.
Hopefully some service will come along that mimics what I was able to do in 2013, I just hope Google Voice doesn't get gimped before then.