Hallo andrerio!
Thank You very much for the information about Dynsite! Very, very interesting.
With Voxalot You can connect and register with Your VSP.
With Voxalot You can define Your dial plans (best cost routing).
With Voxalot You can define call forwarding.
But You need something *to connect with VSP from PC*.
O.K.
Maybe is
Asterisk :: The Open Source Telephony Platform | the right product for You: enough sofisticated, complicated and is *software* for (not only) PC.
Regards,
Fla