I’ve had a series of smartphones throughout the past years (BB 7100t, BB8700c, HTC Hermes/8525 and now N95). Each and everyone of it, I’ve been successfully unlock them legitimately and without paying anyone or going through some online services. That is not to say that those online services are not trustworthy, it’s just that if you have a legitimate phone/contract with any carrier, they will very likely unlock for you upon your request.
In all of my scenarios, I ususally wait about 1 to 2 months into my contract. Then I simply place a call with customer service explaining hat my personal traveling would require the need to unlock the phone. It helps if you can identify a country or just have a casual chat with the rep about your vacation plans. 9 out of 10 are very understanding and would be willing to help you with your request. In the recent years, AT&T would put in a request for me and email me the instructions about 3 days later (even though they claim it could take up to 10 business days).
Tip! I would unlock any phone that belongs to you. It is your rights to be able to use your phone with any carrier (this is more applicable to GSM phones). I’ve done so with many phones in the past with the same method. They’ve all been successful.