Worth mentioning, that for a long time Moscow subway already has free wi-fi (with paid plans too). Moreover, in Moscow you can see Moscow_WiFi_Free in almost every place of city center. Even every bus has a wi-fi hotspot.

However, you need to receive a text message to use the free Wi-Fi, rendering the service less useful for tourists. So it's for some valley where you have a cell plan including SMS, but not decent data.

I believe (but someone should confirm) that incoming calls and SMS are free in Russia, as in most countries.

But sadly no streaming yet

grpc-go (https://github.com/grpc/grpc-go) + grpc-gateway (https://github.com/grpc-ecosystem/grpc-gateway)

Same here. I was sceptical about code generation and the whole protobuf as a base thing but i'm really liking it. Especially when you throw opentracing in the mix.

dialog messenger (https://dlg.im) and sentry (https://sentry.io)

Those are just Scala unicode operators http://scala-lang.org/files/archive/spec/2.11/01-lexical-syn.... They are equivalent to <- and =>

Here comes another question: what's the difference with https://layer.com?

If the technology is 10x better, there doesn't need to be much difference. There's room for more than one provider.