Hi Brian, with Session.SetVariable("transfer_ringback", ${us-ring}); I have message: "[CRIT] switch_channel.c:633 Invalid data (${transfer_ringback} contains a variable)".   Using from managed code:   string stUsRing = _Session.GetVariable("us-ring"); Session.SetVariable("ringback", stUsRing); Session.SetVariable("transfer_ringback", stUsRing);   The bridge works fine.   The question is, using Session is not possible acces directly global vars way ${var_name} ?   Thanks   Diego