In this post I want to show you how you can reduce the login time for Skype for Business Online, when you are using a Proxy.
Skype for Business tries to login directly, if this is not possible in your environment, it is waiting for a timeout. So if you are using a Proxy the login time can take about 30 seconds or more. Thats because the Proxy is only a fallback.
To reduce the time for the login you can use a registry Key to try the direct login one time and do not wait for a timeout response. After that it directly use the configured system proxy.
reg add HKCU\Software\Microsoft\UCCPlatform\Lync /v EnableDetectProxyForAllConnections /t REG_DWORD /d 1 /f
To make sure, that the registry Key is working, you can reboot the System. After the reboot start a login to Skype for Business and check if the login time again.
Please be aware that you can not reduce the startup time of Skype for Business with this improvements.
In this article you can find additional Information from Microsoft:
Enabling Lync/SfB Client to use proxy server for SIP traffic instead of trying direct connection