Had to search a little to find what they use.
In fact 2b uses a SIP VoIP solution.
http://www.voip-info.org/wiki/view/Hong+Kong+Broadband
this link provides with some troubleshooting/ideas.

I guess the next step could be to find a VoIP SIP phone that is known to be fully compatible with this service.

I guess that you probably have some kind of VoIP enabled router where you can connect a phone that uses the service and your network for your PCs being able to access the internet.

It's nice I've gone throught this because one of my customers would like to try a VoIP box that seems to have the same kind of service 2b has... so basically searching for you is also searching for my customer
http://www.vonage.com/index.php?ic=1

I guess 2b has a forum or multiple forums in the appropriate language, that list devices and provide with help.
Most data was only accessible with a 2b account on 2b's site.

To me, skype phones if they are not SIP aren't what is needed. Last time I checked, skype way of working is totally prorietary and not compatible with SIP which is an industry standard.


So in any case I guess our little talk covered most of the possible solutions.