Slingbox works with the Motorola VIP12XX hardware running Microsoft Mediaroom. Mediaroom is used by AT&T in the U.S. as well as Sasktel, Telus, MTS, Bell Fibe and Aliant in Canada. When you set it up, you can use the codes for AT&T.
When you are streaming a Slingbox, the most important factor is the upload speed of the Slingbox location. There won't be any effect on the download speed of the other TVs connected to Sasktel Max.
You can read comments from other Digital Home users about searching for Slingbox in the forums on Telus, Fibe, etc.