No you don't .. the standard modem we recommend for these services is the TP-Link 8950N or 8960N at around $35 and $45 respectively.
If you are really close to the exchange then even the cheapest 8817 works ok.
They are just $25.. so paying big money for a modem to bridge is not worth it..
That is assuming you have or want to buy a Time Capsule.
However I must add one important factor.. PPPOE on the TC is not wholly reliable.. for some it works fine.. for others not at all.. and others like me it is unusable because it won't hold the line for more than a min or two.. which means the internet is very unreliable.
In Australia it is extremely hard to tell you because our phone cabling is so poor both inside and Telstra cables outside.