@kami, blackberry phones do not work (data etc.) without a blackberry service, hence there is no blackberry sold without a service, so it can be unlocked but it will always have customized logos and software for a provider.
For other phones like Nokia, SE, Apple, etc. there are OEM versions as well as service provider versions. So if you are looking for something without the logo then forget blackberry or find a cracked firmware version for blackberry bold and flash a blackberry from Ufone, it has no sticker on it but has Etisalat startup logo and browser logo on it, which will be removed after flashing but it can destroy your phone. You have been warned.