Do I Need a New SIM Card to Switch Carriers?

Tyler Abbott Contributing Writer

Updated 23 March 2026

Contents

Jump to:

What is a SIM card
How do I get a new SIM card?
Standard SIMs vs. eSIMs
GSM vs. CDMA
Should I switch my plan?

Do you need a new SIM card when switching carriers? Long story short: Yes.

If you’re thinking about switching to a different carrier, you’ll need to get a new SIM card for your phone. Carriers can help you port over your phone number and contacts, but you’ll need a new SIM card to activate service with a new carrier unless your phone has eSIM capabilities.

What is a SIM card?

SIM stands for Subscriber Identity Module. This is a mini card or chip that stores data for GSM network phones. All three major wireless carriers (AT&T, T-Mobile, and Verizon) as well as Mobile Virtual Network Operator (MVNOs) like Mint Mobile and Metro by T-Mobile use SIM cards to tie phones to the cellular networks.

Think of SIM cards as keys to a wireless network. Just like you need a specific kind of key to start your car, you need specific kinds of SIM cards to access different networks. AT&T SIM cards give your phone access to AT&T’s network, while Verizon’s SIM cards give you access to Verizon’s network and so forth.

You can usually find your phone’s SIM card on the side of your device. All you need is a handy dandy paperclip to press the button and open up the tray for your SIM card. Check out the best dual SIM phones on the market for enjoying multiple lines of service on one device.

Are SIM cards universal?

No, SIM cards actually come in different sizes depending on your device and model. There is a "standard" size SIM (0.98 x 0.59 inches) that most devices use, and most carriers will send you a "triple-cut" SIM that would fit in any device. Hop over to our guide to SIM sizing for more.

Do I need a new SIM for 5G?

No, 5G access doesn't require a new SIM card. It does, however, require a 5G smartphone. Your SIM simply connects you to your carrier's network—your device model and phone plan determine whether you'll be able to access a 5G signal.

Never underestimate the power of a paperclip.

How do I get a new SIM card?

If you’ve already decided on a new carrier, you just need to go through the checkout process and the new carrier will send you a SIM card in the mail. For some carriers, you can even buy these at retail stores. Make sure to let your new carrier know that you want to transfer your old number when you sign up for the new plan. The checkout process should ask you about porting your old number—if not, get in touch with a customer service rep.

Can I bring my old phone to a new network?

In most cases, as long as your phone is unlocked, you can do whatever you want with it at this point. The caveat is that it must also be compatible with the network you're looking to switch to. Most modern phones can switch easily between networks, but you'll want to check your carrier's website before switching.

A locked SIM means you're still tied to your current carrier. You'll usually have a locked SIM if you haven't yet paid off a phone that you purchased by financing via monthly payments. If you paid for your phone outright, or you’ve already paid it off over time, your device can be easily unlocked and ready for a new SIM card on a new network.

If you want a new number on a new plan, it’s really as easy as signing up for the plan, receiving the SIM card, and popping it into an unlocked phone.

Do I need a new SIM card for a new phone?

As long as you're sticking with the same carrier you're currently with, you don't need to get a new SIM card if you get a new phone. For example, if you're a Verizon customer with an iPhone 12, you don't need a new SIM card to upgrade to the iPhone 13; you can simply swap your current SIM into your new device.

Don't forget a travel SIM!

When you leave the country, you're also leaving your carrier's network. Many carriers have international roaming agreements overseas, but another way to connect while abroad is to get an international or travel SIM. Check out our guide to learn how to use one!

If you're getting a different device type—say, switching from an iPhone to a Samsung—you may need to check that your SIM slot is the same size in order to keep your current SIM. Otherwise, you may need to request a new one from your carrier.

When switching to a new carrier at the same time as getting a new phone, you'll need a new SIM that connects you to your new network. Your carrier will send it to you along with your new device.

Standard SIMs vs. eSIMs

Some newer devices come equipped with an electronic SIM card, or eSIM. Like the iPhone 14, which doesn't include a physical SIM card at all. Unlike regular SIM cards, which are physical pieces of hardware that you can remove from your phone, an eSIM is embedded into your device.

Instead of swapping cards when you change networks, your carrier can digitally activate your phone's eSIM, making it very easy to bring your phone with you when you switch. You can tell if your phone has an eSIM by looking around the edge of your phone's casing—if there's no slot from which to remove a physical SIM card, you've got an eSIM in your device.

GSM vs. CDMA phones

Before the advent of 4G LTE, networks were split between GSM and CDMA providers. Long story short, GSM phones (AT&T and T-Mobile) used SIM cards and CDMA phones (Verizon) did not. Since 4G LTE phones came around, new iPhones and Android devices are compatible with both GSM and CDMA networks.

This is good news for all of us because we don’t need to stress about whether our phone is a GSM or CDMA phone and whether or not it will take a SIM card. Basically, any unlocked iPhone after iPhone 5 or any unlocked Android phone since 2013 should be compatible with SIM cards.

Beware of SIM swapping

SIM swapping is one of the latest tactics used by scammers to steal your information—and frequently your identity. It's very simple in theory, yet catastrophic in practice, as it allows thieves to take control of your calls and messages, and from there even more personal information. Check out this SIM swapping article to learn more about how it works, and what you can do to protect yourself.

Should I switch my cell phone plan?

In most cases, yes you should! Switching deals are usually a great way to get discounted plans or phones. Plus, some carriers will even pay you to switch.

Generally, MVNOs offer some of the best switching deals and low-cost plans. These smaller carriers operate on the Big Three (AT&T, Verizon, and T-Mobile) networks at a fraction of the cost. Mint Mobile's Unlimited Plan starts at $30/month ($15/month for the first 3 months) on T-Mobile's network. Or, you can pick Visible's basic unlimited plan for unlimited data and an unlimited mobile hotspot on Verizon's network for just $25/month.

Check out some of the other popular MVNO unlimited plans below:

#1	XFINITY Mobile	XFINITY Mobile Mobile Select Plan Unlimited 4G LTE/5G data Available on 1 Major 5G Nationwide network in select areas with compatible devices Unlimited mobile hotspot data Deal: Get a FREE 1 year of Xfinity Mobile Select Plan with Xfinity Internet required $0.00/mo (for the first year of service) <br>Regular rate of $30/mo. thereafter View Plan	$0.00/mo (for the first year of service) <br>Regular rate of $30/mo. thereafter	View Plan
#2	Astound Mobile	Astound Mobile Unlimited Data Plan Unlimited 4G LTE/5G data Available on 1 Major 5G Nationwide network in select areas with compatible devices Unlimited mobile hotspot data Deal: Get this Unlimited Plan for Free for one year of service with Internet required $0.00/mo + $14.99 Upfront View Plan	$0.00/mo + $14.99 Upfront	View Plan
#3	Boost Mobile	Boost Mobile Unlimited Plan Unlimited 4G LTE/5G data Available on 3 Major 5G Nationwide network in select areas with compatible devices No mobile hotspot data Deal: Get this Unlimited plan for only $10/mo. for the first 3 months of service with Boost Mobile! $10.00/mo with AutoPay View Plan	$10.00/mo with AutoPay	View Plan
#4	Cricket	Cricket 3-Month Unlimited Plan Unlimited 4G LTE/5G data Available on 1 Major 5G Nationwide network in select areas with compatible devices No mobile hotspot data Deal: Get this plan for only $45 for the first 3 months or $15/mo. $15.00/mo $45 advance payment for 3 months (equals to $15/month)<br>regular rate for 3 months is $120 (equals to $40/month) + $9.99 Upfront View Plan	$15.00/mo $45 advance payment for 3 months (equals to $15/month)<br>regular rate for 3 months is $120 (equals to $40/month) + $9.99 Upfront	View Plan
#5	Google Fi Wireless	Google Fi Wireless Unlimited Essentials for 1 Unlimited 4G LTE/5G data T-Mobile 5G Network in select areas with compatible devices No mobile hotspot data Deal: Get 50% off this plan for 12 months when you bring your own Pixel phone and activate a new line on Unlimited Essentials plan $17.50/mo View Plan	$17.50/mo	View Plan

If you can afford to spend a bit more money, plans from the major carriers can offer a bit more premium data and perks. AT&T's top Premium 2.0 plan includes unlimited premium data, a 100GB mobile hotspot, and 4K streaming for $90/month. Verizon's Unlimited Plus plan includes unlimited data and a 30GB mobile hotspot for $80/month. You can get extra perks like the Disney Bundle or a 100GB mobile hotspot for $10/each per month. Finally, T-Mobile offers Experience More, which includes unlimited premium data, a 60GB mobile hotspot, 4K streaming, and subscriptions to Netflix and Apple TV+ for $85/month.

#1	T-Mobile	T-Mobile Essentials Saver Unlimited Unlimited 5G & 4G LTE with 50GB of Premium Data T-Mobile 5G Network in select areas with compatible devices Unlimited mobile hotspot data Deal: Get up to $800 via virtual prepaid MasterCard when you bring an eligible phone, activate a new line on select plans and port-in your number and switch from select carriers $50.00/mo with Auto-Pay - Taxes & Fees NOT included View Plan	$50.00/mo with Auto-Pay - Taxes & Fees NOT included	View Plan
#2	T-Mobile	T-Mobile Experience More Unlimited Unlimited 5G & 4G LTE with Unlimited Premium Data T-Mobile 5G Network in select areas with compatible devices Unlimited mobile hotspot data $85.00/mo with Auto-Pay + Taxes and fees View Plan	$85.00/mo with Auto-Pay + Taxes and fees	View Plan
#3	Verizon	Verizon Unlimited Plus Unlimited 5G Ultra Wideband Verizon 5G Network in select areas with compatible devices 30GB mobile hotspot data Deal: Get $10 off per line for 1 line via monthly promo credits over 36 months. For new customers only $70.00/mo + Taxes & Fees. Price includes AutoPay & Paperless discount. + $40 Upfront View Plan	$70.00/mo + Taxes & Fees. Price includes AutoPay & Paperless discount. + $40 Upfront	View Plan
#4	Verizon	Verizon Unlimited Ultimate Unlimited 5G Ultra Wideband Verizon 5G Network in select areas with compatible devices Unlimited mobile hotspot data Deal: Get $10 off per line for 1 line via monthly promo credits over 36 months. For new customers only $85.00/mo + Taxes & Fees. Price includes AutoPay & Paperless discount. + $40 Upfront View Plan	$85.00/mo + Taxes & Fees. Price includes AutoPay & Paperless discount. + $40 Upfront	View Plan
#5	T-Mobile	T-Mobile Experience Beyond Unlimited Unlimited 5G & 4G LTE with Unlimited Premium Data T-Mobile 5G Network in select areas with compatible devices Unlimited mobile hotspot data $100.00/mo with Auto-Pay + Taxes and fees View Plan	$100.00/mo with Auto-Pay + Taxes and fees	View Plan

Tyler Abbott

Contributing Writer

Tyler is a Contributing Writer who's always on the lookout for the best wireless tech so he can watch all the sports and still have enough time to hang out with his baby. He has written about streaming, wireless, and TV for over three years.

Read full bio