Do I Need a New SIM Card to Switch Carriers?

04 April 2017

Do I need a new SIM card?

Do you need a new SIM card when switching carriers? Long story short: No. 

You can bring your SIM with you to another carrier. But there are plenty of factors to consider. 

When you’re thinking about switching cell phone carriers, you need to take care of a couple of  things. Don’t get too excited about an ideal cell phone / carrier situation until you know for sure where you stand. First, find out if you even own the phone or if you owe money. Read this article on switching carriers now if you’re unsure of what to do.

In this mini-guide, we’re going to address some basics so you can find out what to do with your SIM card and whether or not you need a new one. As always, you never want to just jump into a brand new cell phone carrier contract without comparing cell phone plans first. 

What the heck is a SIM card?

SIM stands for Subscriber Identity Module. This is a mini card or chip that stores data for GSM network phones. Of the big four carriers, AT&T and T-Mobile are on the GSM network. Unsure of whether you’re on a GSM network or not? Go here.

The SIM card in your phone holds onto your identity, location, network data, security keys, contacts, and saved texts messages. Basically, if you’re on AT&T or T-Mobile, the SIM card is your phone. The device you’re holding is just a really rad-looking case with a beautiful screen.

remove sim cardNever underestimate the power of a paperclip.  

Unlocking the SIM card before switching carriers

In a perfect world, we’d be able to grab a SIM card and plop it into any phone on any network and give it a new lease on life. Unfortunately, that's not the case. While the physical portability with these cards is easy, network is the real concern when switching carriers. 

There are two scenarios. Let's review both.

Scenario 1: Let’s say you want to switch from Verizon to Sprint. Chances are that you don’t have a SIM card since both Verizon and Sprint are CDMA networks. CDMA networks don't use SIM cards. In this instance, you just need permission to bring your phone from Verizon as well as permission from Sprint to use this (Verizon phone) with them. This double-checking and permission getting is due to the fact that carriers on CDMA networks (like Verizon and Sprint) are not obligated to let you use your phone on their network just because they are both CDMA phones. This is because carriers want you to buy a phone with them. 

Scenario 2: If you’re switching carriers from GSM networks like AT&T to T-Mobile, things are easier. Once your phone and any outstanding fees are paid, you are free to take your GSM network phone and bring it to any other GSM carrier. In this scenario, customers think they're paying for their phone itself but in reality you're also paying for the SIM card and all of the data on it. Now the SIM card is officially unlocked and you have your phone number and data all ready for a brand new carrier (or new phone if that’s the case). 

But wait. There's more:

TIP #1: If you are stuck between carriers or devices, you can use a device called a SIM card reader to upload any data from the card to your computer so you don’t lose anything. 

TIP #2: If you’re just looking for a guide on traveling and want to know how to use a prepaid SIM card for local numbers, read this helpful guide on international travel and SIM cards right now.

What do I do with my SIM card now?

Keep the SIM card if you're just switching to another GSM network carrier. Once unlocked, you can move right on it and make yourself at home with your new carrier. If you're switching to a carrier on the CDMA network, say goodbye. You'll most likely be buying a new phone in order to take advantage of this new network. You can keep your SIM card and save any data from it. 

Switching carriers should never be a stressful event. If you take anything away from this mini-guide, know this: 

  • You have a right to an unlocked SIM card and phone after you've paid for the device (and any outstanding fees) in full
  • You can bring your device and SIM card with you to another GSM network carrier
  • You cannot bring your SIM card to a CDMA network carrier

If you decide to go from T-MOBILE to SPRINT, you will pay more out of pocket because you'll have to buy a new phone. Compare on this helpful bring your own phone guide here to see which carriers are doing what.

You can start comparing cell phone plans on the GSM networks here: 

Compare Carriers to Find the Perfect Cell Phone Plan



Some things improve with age

Your phone plan is not one of them.

We monitor 118,241 plans from 33 carriers. Haven't changed recently? You're probably on the wrong plan.

Get the right plan

  • Sprint
  • T-Mobile
  • Verizon Wireless
  • Cricket
  • The People's Operator
  • Ting
  • AT&T
  • Boost Mobile

Compare phones and plans from the following carriers...

Featured Deals

Cell Phone & Wireless Deals Every Week

Our pick of the Hot Deals from every carrier, handpicked and fresh

T-Mobile Cell Phone Deals

All the deals on T-Mobile every week

Sprint's Wireless Deals & Best Plans

All the deals from Sprint, updated every week

Straight Talk Cell Phone Deals

All the deals from Straight Talk, updated every week

Sites that use our comparison technology

Our comparison technology is used by many publishers to evaluate products and services. You can find our technology and service on:

Advertiser Disclosure & About this Service

WhistleOut maintains a broad list of service providers and we endeavour to include at least the top ten service providers in every category so that you can make a transparent choice. When you see a 'promoted product' or a product with a 'go to site' button it means that WhistleOut is earning a transaction click fee for the referral. We audit the prices in our database regularly and we don't alter the ranking of products in our organic search based on any commercial relationship. Find out more here