People around the world still want Sidekicks, which is awesome. But the problem is, as discussed here (up one level) is that the Sidekick 3 can't be taken to carriers outside of T-Mobile.

That hasn't stopped some people. Which is why this page exists.

Other carriers in the world carry the exact same device (with some differences), but they're not called the Sidekick. Only T-Mobile calls what we know as the Sidekick by that name. Danger (the makers of the software that powers the Sidekick) originally called it the Hiptop. This is the case with carriers other than T-Mobile. I (justarep) have done the research so you don't have to!

(links current as of October 26, 2007)
Australia -Telstra - Hiptop Slide
Germany-T-Mobile Germany - Sidekick Slide
United Kingdom -T-Mobile UK - Sidekick Slide
Canada - Fido - Hiptop 2 (discontinued)
Cayman Islands - Cable & Wireless Cayman Islands - Hiptop2 (discontinued)

T-Mobile's Dirty Little Secret:
USA -SunCom - Hiptop3 (discontinued)
T-Mobile has the US exclusive on the "Sidekick 3", but SunCom, a smaller carrier that services North and South Carolina, Georgia, Tennessee, and Puerto Rico, has the Hiptop 3, which is virtually the same device. However, SunCom is much smaller than T-Mobile, so unless you live in one of those four states/one territory, you're fairly out of luck.

SO! If you live in one of the above countries and you can get service from that carrier, you can enjoy Sidekick service at home. Some differences exist in available software, updates, and downloads, but the basic function of the device is the same. If you do not live in Australia, Canada, the Cayman Islands, Germany, the UK, or the US, you're out of luck for getting a Sidekick, for the reasons explained here.

Discontinued Carriers
Some carriers have carried Hiptop devices in the past, but I can't even find links to them. (The Fido and C&W links above to discontinued Hiptops are linked because they are still online.) These carriers are:
E-Plus (Germany)
T-Mobile Austria (Austria)
StarHub (Singapore)
KPN (Netherlands)
Edge Wireless (USA)

This information is collected from
http://www.poweredbydanger.com/partners/operators
Please note that some of the operators below may only carry Danger-powered products in retail stores and not online. Check with your operator for details.