Sony phones don't sell well enough for Telus to bother with. Bell and Rogers seem to be carrying less and less Sony devices as well. If you happen to find one at another carrier in Canada or even some US or international models. They will more than likely work to some degree on the Bell/Telus network. Just do your research before buying to make sure it is compatible with the network.
This makes me wish Telus offered an a la cart way of purchasing phones through a subsidy plan. Basically ordering it online through the site or in-store, having to wait for it as devices would be ordered based on each customer, and paying a fair a la cart fee for getting what you want. Obviously, a waiver for network compatibility would have to be signed but this could definitely give consumers more options. All special order devices would only have manufacture warranties, if available at all in Canada. Devices would literally be the cost, plus import fees, taxes, shipping, and so on but divided over 12 or 24 month terms and then there is that fee for being an a la cart order. It would be more expensive than buying it outright but that doesn't seem to be a viable option for a lot of people.