MSN Messenger voice conv works with dial-up, but not with cable modem

[seadm]

Hello, I am using MSN Messenger 4.6 on Windows 95. When I am connected via phone line, I can have voice conversations with the other people. I have recently installed a cable modem and since then I cannot have a voice conversation with MSN Messenger. I tried it with contacts that use both cable internet and dial-up. Sometimes it cannot find the other computer and sometimes it establishes a connection and immediately breaks it.
When I use dial-up it is still good, I can talk.
I believe this is either a firewall or setup related problem. Please let me know if you experienced a similar situation and could help.

 

[netbum]

Is this a single device behind a cable modem or are using a router behind the modem for multiple computers?

 

[seadm]

It is a single laptop connected directly to a cable modem.

 

[seadm]

I found out what caused the inability to talk. I have a firewall which has to be deactivated in order to have voice conversations.

 

[tunneling]

RealTunnel has developed a new generic real time proxy (

http://www.realtunnel.com)

that enable you to use MSN Messenger for voice and video behind any FW/NAT configuration (without opening any ports on FW).

Cool stuff. Still beta, so you'll have to request the download.