I know that when you get an unlocked phone you can then use any sim card. So when travelling it permits to save money.
Now, I'm not very knowledgeable with smart phones, but if I understand correctly unlocking a phone is worthwhile if you do NOT buy it. But the other way to get a phone is through a providers and they all have a 3 years contracts.
So, you are on a lease with the company and my question is, if you are already paying a monthly fee, what do you save? Except if you are abroad.
And if you change the sim card for another company, won't they notice that you never use their services?