T-Mobile and AT&T both have different carrier networks, leading people to ask the question “Can I use an AT&T phone on T-Mobile?” The short answer is yes.
Because both AT&T and T-Mobile phones use a SIM (Subscriber Identity Module) card, each SIM card is uniquely identifiable. However, each network uses a different GSM (Global System for Mobile Communications) frequency.
AT&T phones will work with the T-Mobile GSM frequencies, but it is first necessary to unlock your phone. You can accomplish unlocking your phone through the AT&T web portal or through manual methods, though the web portal solution is most ideal.
Let us learn more in detail!
Unlock Your Device
The most important requirement to switch carriers is to unlock your device. AT&T ties SIM cards and supported phones together with their network.
Without unlocking your mobile phone, switching carriers will not work.
T-Mobile will not accept mobile devices to their network from other carriers unless they have first been unlocked for legal purposes including contracts and mobile device theft.
Fraud and Legal Requirements
Unlocking an AT&T mobile device has several prerequisites. If you want to know will an AT&T phone work on T-Mobile, there are several considerations, as follows:
- The mobile device was not stolen
- Your device is signed up for up to 60 days
- You have no early contractual termination fees
- You agreed to AT&T’s terms and conditions
How Can I Use an AT&T Phone on T-Mobile?
AT&T created these rules and stipulations to prevent people from stealing a phone and switching carriers.
It isn’t possible to switch to T-Mobile without meeting the aforementioned requirements to unlock your phone with your old SIM card.
Method #1: Unlock Your Phone with AT&T Online
To unlock your phone manually, visit the AT&T website. This method presumes that your current phone has a SIM card and a valid number.
Not everyone is qualified for unlocking their phones and SIM cards, however.
To check if you qualify, please refer to the following steps:
- Visit the AT&T website to unlock your mobile phone.
- Select Unlock Your Device.
- Enter your current phone number.
- Read and agree to the terms and conditions
- Follow the prompts and the email link.
Note: AT&T responds with an email within 24 hours. However, your request may be denied.
Two probable reasons for rejection include a stolen device and also late payments to AT&T.
Method #2: Get a New SIM Card
Another way to transfer from AT&T to T-Mobile is to simply get a new SIM card. But be forewarned: getting a new SIM card means that your phone number will change.
This may be undesirable for some people for varying reasons. Some people simply don’t want to memorize a new phone number.
But you should also consider everyone you call and text, as well as any web accounts with which you secure via your mobile phone number.
If you have a long list of contacts on your phone, updating your SIM card could make you unreachable without telling all of the contacts of your updated number.
Note: New SIM are an industry standard and will work with any phone.
However, even after purchasing a new SIM card, you may still need to manually unlock your phone before switching to a new service.
Method #3: Unlocking Samsung Mobile Devices Manually
Many Android devices have similar manual unlocking procedures.
If you have a device that is purchased secondhand and was previously locked to the AT&T network (and that phone doesn’t have a current carrier plan), you can manually disconnect through the operating system.
Use the following steps on Samsung devices:
- Open the Settings menu.
- Select Connections.
- Select Connection Settings.
- Tap the Network Unlock option.
- Restart your device.
Also, I would highly advise backing up all of your phone data before switching carriers.
Though switching phone providers won’t delete your data, it’s always good to have a backup, especially if you change your mind and decide to get a new phone.
Note: If you use this method to unlock your phone but still have a SIM card installed from your AT&T plan, you may not switch carriers.
Only AT&T can help unlock a phone using a SIM card from one of their accounts.
Method #4: Unlocking LG Mobile Devices Manually
If AT&T won’t allow you to unlock your phone and SIM card on an LG device, you can use the manual procedure.
LG devices have a slightly different unlocking method, as follows:
- Open the Settings menu.
- Open the Network and Internet menu.
- Select Mobile Networks.
- Select Network Unlock.
- Restart your device.
This method presumes that you are discarding your SIM card and installing a new one. If you are using a SIM card from an AT&T plan, you must use the unlocking steps in Method #1.
Method #5: Unlocking iPhone Devices (Backup & Erase)
As with the previous two methods, to unlock an iPhone manually, it is safer to get a new SIM card to switch to T-Mobile.
You can, however, use the Backup & Erase method, using the following steps:
- Create a backup in iCloud.
- Erase your phone.
- Use your backup file to restore your phone.
I would recommend first seeing if your phone qualifies for unlocking as mentioned in Method #1.
Erasing all of the data on your phone could be risky and cause loss of data if anything should go wrong with the backup and restoration process.
Method #6: Technical Support
The last option is to call technical support before switching to T-Mobile.
It is easier and faster to use the web portal (Method #1) to unlock your phone, but tech support is available 24X7 to assist customers.
You can call 1-800-288-2020 for general assistance (hours may vary in your region).
Note: T-Mobile does allow transfer assistance to alleviate early termination fees with AT&T for those who are eligible.
Though T-Mobile does help reduce the cost of fees, to keep your old phone and number, you will still need to unlock your phone.
Read Next: How to Get Netflix with T-Mobile?
Bottom Line
Many people wonder, “Can I use an AT&T phone on T-Mobile.” Legally, you can, but only if your mobile device is unlocked.
The best way to unlock your AT&T phone is to visit the website and go through the unlocking steps mentioned in Method #1.
T-Mobile cannot unlock your phone for you; instead, AT&T must unlock it for current customers.
Lastly, note that only unlocking your mobile device and signing up with T-Mobile doesn’t exempt you from obligations with AT&T.
Even with a new T-Mobile plan that helps mitigate early termination fees and contracts, you may still be liable to AT&T contract obligations.
Kevin has over five years of experience working in various Tech startups and providing Technical solutions. He has contributed to many Tech publications and websites. Check out more about him here.