Incoming call work but without ringing in windows

Question

I just installed zoiper and setup 2 voip lines (accounts). It works perfectly both for incoming and outgoing calls. The problem is that when I receive a call I just know it because a small popup window appears informing about the incoming call, but no ringtone sounds (meaning that if I'm not looking at the screen I can not know about the call). How can I solve this problem ? Any ringtone is good to me ... 

Note: I'm using Win Server 2008 R2 (which usually works like Win 7 64bits)

Comments

solved ... the problem was in the device used as ringing device. Did not see there was a specific device for ringing and was set different.

Thanks