Hi Russ,
Yep. When you goto Kogan/activate sim, it will ask if you want a new mobile no. or transfer your existing one over. In my wife's instance she went from Optus to Kogan/ Telstra. It takes a couple of hours to port thru' but you'll get an SMS when it's done. Very simple process.
I'm planning to upgrade my wife's plan from $29 monthly to the $299 one. It's a pretty good deal.
Norm
