For UFB with Bigpipe, you do not need a modem. However, you *do* need a router capable of handling the awesome speeds UFB provides.
Our personal favourite is the TP-Link Archer C2 (listed below). It's a good combination of quality performance and value for money.
However, if you are one of the lucky ones on a Gigatown plan, it's probably worth investing in something better to make the most out of those speeds.