Are GSM Bell/Telus phones fully interchangeable with Rogers/Fido?

[Sureshot324]

If I get an unlocked Bell or Telus GSM phone, will it fully work on Rogers/Fido if I put a Rogers SIM card in. How about the other way around?

 

[RedRooster]

Yup! My Telus Optimus 7 works on Fido just fine, after being unlocked.
A minor SMS timestamp issue, but everything on the phone works perfect.