Asterisk 11 – Gateway Grandstream GXW4008. Call Waiting problem

hello good afternoon everyone,

I need help with a failure that only occurs with GXW4008 equipment. When I call in the second line (call waiting) makes the first call silent for a few seconds. I did the tests with other CISCO LINKSYS SPA8000 equipment, with this I did not have this problem. The second line usually played without leaving my first line changes.

I use the FreePBX version 12.0.33 with the asterisk 11.