Can you use a T-Mobile Sidekick 3 with Cingular plans and SIM cards?
It won’t work even if it is unlocked. The purpose of unlocking a Sidekick is to be able to use it overseas with a different company that has access to the Sidekick network. In the United States, T-Mobile is the only company that provides access to this network. If you stick a Cingular SIM card in an unlocked Sidekick, unlike most other GSM phones, it will just continue to search and reject your SIM card. Many people have tried this and it’s failed – save your money and either switch to T-Mobile or look at what data devices Cingular offers. (I personally like the Peral in their line-up.
