如何在ISA 2004环境中使用Live Messenger(MSN)视频连接(未解决中）

目的：
在部署ISA 2004防火墙的环境里，内网用户可以成功和内网用户或者外网用户使用Live Messenger(MSN)的视频连接。

现在的现象：
1.无论由内网用户还是外网用户发起的Live Messenger(MSN)的视频连接都不能成功，没有报错信息，MSN只是提示一直在尝试连接对方视频。
2.内网用户可以和内网用户成功使用MSN视频连接。

相关说法：

1.How To Add Support for MSN Messenger Net2Phone in Internet Security and Acceleration Server 2000 [url]http://support.microsoft.com/?id=284554[/url]

2.Steve Foster [SBS MVP]
You will not get MSN Messenger video/audio to work through ISA. I don't think ISA2004 will support it either.
[url]http://msmvps.com/blogs/kwsupport/archive/2004/11/03/17834.aspx[/url]

3. zzz343.
MSN Vocie and video donot work with ISA, because it donot support uPNP protocol. Some time it
works or some time it don't. If other person connected directly to iNternet sends you request for voice conversation then it may work, but it's not always work.
[url]http://forums.isaserver.org/m_140009600/tm.htm[/url]

4.Edward Tian(MSFT) [Microsoft CSS Online Newsgroup Support]
In order to use MSN Messenger's Audio/Video feature, we need to make a lot of changes to the firewall.Since the new version of MSN Messenger may change the ports that it uses, we do not have a perfect solution on ISA 2004. [url]http://www.mcse.ms/message1767165.html[/url]

原理：
1.Windows Messenger in Windows XP: Working With Firewalls and Network Address Translation Devices

2.Instant Messaging with ISA Server

(未完待续中...）