[Freeswitch-users] Voice quality of bridged call comparing to direct connect

Dear all, I have a accounts with sipgate.co.uk. When I connect directly form X-lite to sipgate with only PCMA codec. The voice quality is good. Recently I set a FS server on Linode VPS and use FS to bridge call from sipgate to X-lite on my computer, The voice quality become much worse with lots of noise. If the call is bridged through skypopen to my skype account, the quality is much better. If the noise is cause by my network speed or PCMA codec, how can sipgate's server avoid it? Is there any way to reduce noise of the bridged call? Thanks.