MSN and ports opening

On NT4 using ms-proxy 2.0 and the latest msn, I have not been able to sign in neither any of the network users. on the help this is the listing microsoft has.

"To configure firewalls that use a transparent proxy server
If you are using a transparent proxy, such as Microsoft Proxy Server version 2.0 in combination with the Microsoft Proxy Client, the users behind your firewall do not need to make any special settings in the MSN Messenger Service client on their computers.

Tell your network users: Even though they use a proxy server, they MUST NOT check I use a proxy server on the Connection tab of the Options dialog box in MSN Messenger Service (Tools, Options).

Important:

To enable instant messaging, make sure that outgoing TCP connections to Port 1863 are enabled.
To enable voice communications, make sure that outgoing TCP connections from Port 6901 are enabled. Also, you need to enable UDP packets where either the source or the destination port is 6901.
To enable file transfer, make sure that you enable both incoming and outgoing TCP connections to this range of ports: 6891 to 6900. This allows up to 10 simultaneous file transfers per sender. If you open only Port 6891, users will be able to do only one file transfer at a time. "

the site is "http://help.msn.com/EN_US/HelpWindow_msg.asp?Topic=InfoTech.asp&INI=messengerv3.ini&SearchTerm=nogol&S_Text=MSN+Messenger+Service&H_APP=MSN%20Messenger%20Service&BrandID=MSMSGS&Fi lter=messenger"

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Senior Software System Specialist