XenCall Problem (Technical Issue)

[Joe Bagwin]

Hi, I'm new here at BiggerPockets. I need help regarding a problem with XenCall. There's a problem when I'm on a call, sometimes I can't hear the other end of the line and sometimes it's the other way around. 

If someone has tried this, it would be very helpful to share your solution. I'm also thinking of opening ports on my modem but I just don't know what those ports are.