Fongo has nothing to do with your sim card. It's a VOIP app you can run from many device, even ones without sims.
If you want to port your Rogers number to fongo go to their website, pay the $25. In a few days Fongo will have your number.
Afterward, if you want calls to your old rogers number to reach your Tbaytel voice line (ie Thunder Bay Phone number):
you can setup Follow Me (Call Fwding) to your new Thunder Bay phone number. Just make sure you top up your Fongo account with $5+ as TB #s are Long distance
Else if you want to take your calls over data through Fongo, keep the app running on your phone. Also keep in mind txt msgs from your ported Rogers number will have to go through fongo. So youll need the fongo app running to receive txts that are sent your ported rogers number. For outgoing txt youll need to buy a Fongo txt package.
Check it all out at fongo.Com