I have a 9800 and I need to tether using VPN AT&T Net Client to access my companies intranet. I can tether however can only access internet. I have AT&T Network Client version 7.6.3.2012 on my laptop. Any suggestions?

You may not be able to do it. Some providers place firewalls on their networks to prevent VPN connections. Others simply don't have their IP routing set up in such a way that VPN connections can get out. Another possibility is that your VPN uses an odd port that isn't allowed. I don't know what the story is for Bell or for your company VPN, but those are a few of the things that can happen.

For what it's worth, I have no problem connecting to my company's Juniper VPN over Verizon LTE or 3G.

I have the ATT client and the Cisco client on my PC. I found the Cisco easy to use. The ATT client had some problems. I would check with your company and see if there are any IT policy restrictions on the BB. My company restricts all BB's unless a request is made to allow tethering. As dc/dc said, the firewall must allow it.