If it operates on the broadband side of the line, there shouldn't be an issue at all. Card machines that run off the same phoneline as a broadband service can cause intermittent connection and slow speed, however if it's running through the router that isn't a problem. What I would say is that your setup should be compatible but when they say it isn't supported, it may just mean that the helpdesk won't provide you with any assistance. Typical attitude is that if your broadband connection works from your PC/Laptop, then it's working. If you're going to be using a BT Business router the only additional information you'll need are the LAN settings, in case your card reader isn't using DHCP (receiving its address information automatically from the router).
IP Range: 192.168.1.xxx
Subnet Mask: 255.255.255.0
Default Gateway (Router IP Address): 192.168.1.254
Also, some merchant services need like to authenticate your card machine. To do this, they'll need your IP address. This is usually a one-time-only request, so you don't need a static IP. The easiest way to find out what your current static IP address is would be to go to http://www.whatismyipaddress.com and it will show you there.
Finally, if your card merchant asks you to open ports and you're using a BT Business router then Technical Help will assist if you know which ports you need to open, and the device is attached to the router and ready when you call.
Hope this helps.
