You either need a modem or, more helpfully a router with a built in modem (like the BT Homehub). If the Homehub is that biggish white or black unit with facility to add a cordless phone, what's wrong with it ?
I have to say I rather agree about the Homehub -- I have one found in the garbage and it seems to periodically lose any changes I make to the settings. I've played with other Thomsom units and they were unpredictable too.
You may be happier dumping the Homehub and asking your dealer to swap the new Dlink for an integrated router/modem oif the same brand (or preferably Netgear which are simpler to set up).