I am having a problem with call transfers. When the call is transfered to another extension the caller hears a lot of static. In the background you can barely hear the caller. The static only appears after the transfered to extension picks up the call during the rest of the call the sound is perfect. The setup is 3CX version 7.0.4249.0 with Grandstream GXW4104 and Linksys SPA922 phones. Any ideas what could be causing the problem??