Linux – Connect Skype For Linux Beta through proxy

How are you guys?
I'm getting the following issue. I was trying to fix it of several ways but without success.
In our organization, to navigate through internet, you need to configure the proxy server.

I have installed Skype for Linux Beta (v5.3.0.1) and I'm getting the following message when I open it.

Sorry, we couldn't connect to Skype.
Please check your internet connection and try again.

When I check Debug Logs, I get the following message:

[Mon, 31 Jul 2017 11:24:12 GMT][INFO][AuthenticationManager] Redirect to login at login.live.com/oauth20_authorize.srf?client_id=00000000480BC46C&redirect_uri=h
ttps%3A%2F%2Flogin.live.com%2Foauth20_desktop.srf&scope=service%3A%3Alw.skype.com%3A%3AMBI_SSL&response_type=token&cobrandid=90010&locale=en-US&client_flight=hsu%2Chlm%
2Chld%2CReservedFlight33%2CReservedFlight67&psi=skype&uaid=5c02b3d4d7b7e468f7ef81d0cfbefafa&lw=1

[Mon, 31 Jul 2017 11:24:12 GMT][WARN]Failed loading page. [-102] ERR_CONNECTION_REFUSED. Url: login.live.com/oauth20_authorize.srf?client_id=00000000480BC46C&re
direct_uri=https%3A%2F%2Flogin.live.com%2Foauth20_desktop.srf&scope=service%3A%3Alw.skype.com%3A%3AMBI_SSL&response_type=token&cobrandid=90010&locale=en-US&client_fligh
t=hsu%2Chlm%2Chld%2CReservedFlight33%2CReservedFlight67&psi=skype&uaid=5c02b3d4d7b7e468f7ef81d0cfbefafa&lw=1

I have to remove https:// from the URLs because I'm new here. The weird thing is, that when skype starts, it seems to recognize the proxy (It is a assumption)

[Mon, 31 Jul 2017 11:24:11 GMT][INFO][EcsConfig] Downloading ECS Config

[Mon, 31 Jul 2017 11:24:11 GMT][INFO][HttpsRequest] [1c4925] Sending request to GET https://a.config.skype.com/config/v1/SkypeElectronWrapper/1427_5.3.0.1?ConfigOption=
release&clientId=5c02b3d4d7b7e468f7ef81d0cfbefafa, Proxy: true, Attempt: 1/1

In my home I don't need proxy and it works like a charm

I tried also modifing the starter script (http://xpo6.com/skype-for-linux-behind-a-proxy-server/), proxifing the skype with tsocks, but all without success.

Maybe someone here has the magic solution (I hope it).

Thanks in advance, and please, if you need further Information, I could provide it.

Regards