When you move your SIM to a new phone, you keep the same cell phone service. SIM cards make it easy for you to have multiple phone numbers so you can switch between them whenever you like. These phones have to be either provided by your cell phone provider or they have to be unlocked.
With unlocked phones, you can always switch your phone service between different phones as easily as popping out the SIM card and moving it. You can also use different phone service plans in a single unlocked phone, say one for work and one for personal, by switching the SIMs. The opposite of an unlocked phone is a locked phone.
In contrast, only SIM cards from a specific cell phone company will work in its locked phones. These phones were locked to protect subsidies, i.e. the amount that your cell phone operator subsidized to have you sign a contract with early termination fees.
As we have had a lot of comments and questions, we have updated this post with a few examples.
- Your phone is on carrier A. Your new phone is on the same carrier. Simply put the SIM card into the new phone and you are ready to go!
- Your phone is on carrier A. Your new phone is on carrier B. You need to call carrier B to move your old number to the SIM card carrier B gave you.
- Your phone is on carrier A. You have a new unlocked phone. Just put the SIM card in the new phone and that’s all you need.
These days your SIM really only holds your account information. But it can hold your contacts. If you want to learn more please read this article on saving contacts.
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