I have seen the same thing with USA 1800 numbers. SOmetimes they return
1641641800XXXXXXX@tollfreefateway.com and other times the same number returns I think it is like
1800XXXXXXX@anotherdomain.com (where anotherdomain is the toll free Michigan? Gateway that never seemed to work??).
At times I have even seen 18000 numbers with valid entries show the tollfreegateway.com URI.
I believe something is not quite right. You can test this on the SipBroker ENUM lookup page. It displays the same result. Just do several searches for the same toll free number and you will probably see it.
Mark