[Serusers] audio and video port lost ???

Hi: Merry Christmas everyone. When I use SER as proxy server, I found a strange problem. My SIP UA have audio and video two media stream. After transfered by SER, the SIP message recieved by my callee UA lost its port information. And I tested it on the sip.iptel.org's SER, this time the audio port info is not lost, but has changed. The video port is still lost( I wonder whether this is caused by NAT). My SER is located in the same private network, why the SER lost the audio and video port info while other info is untouched ???? Appreciation for your help and instructions Best Regards. -- IPv6 on Everything, Power to Everything. Everything runs on Linux -------------------------------------------- Sun Zongjun Sinux Sun Programmer BII Group Holdings Ltd (BII Group) E-mail: zjsun(a)biigroup.com Web: http://www.biigroup.com; http://www.ipv6.net.cn Phone Office: +86-10-65836569-175 Fax Office: +86-10-65836565