Spark 2.5.8 x Windows Vista

Hello Everybody!!

I have been having problems with spark 2.5.8 running in Windows Vista SP 1.

When I want to do a Voice Call, the client machines cannot connect each other. If I tray to connect with Win XP, voice call works pretty well!

All the machines are in the same network and there is no firewall betwin them.

I tried to install the newest Spark 2.6.0 Beta but it doesn´t have option to make voice calls and, if someone call me, Spark 2.5.8 returns some errors to the spark 2.5.8 user.

Can someone help me?