I have the 3cx software working very well on my Lan but when I try to use Softphone,or grandstream 285 outside on the internet i get no voice. The phones all regester correct and you can call to them and they ring . You can call back in the 3cx phone on Lan from the outside internet phone and they ring also. But no Voice??? I have done the settings for Grandstream per the instruction of 3cx manual. I have also opened ports on both sides for 5060-5064,5090-5094,9000-9049. Any thoughts???