
We have covered this topic of locked vs. unlocked phones in the past, but it’s still one of the most common questions we get. Therefore, we’ve decided to write another article describing it.
Many carriers still limit the phones to only work on their network, at least till you tell them to do something about it. Legally you have the right to unlock your phone (more details in Can I Unlock my Phone), but you have to get permission from the carrier. Locking your phone to a network is probably the easiest way to keep a customer. But to be fair, a common reason for locked phones is that the carriers can offer lower upfront payments. You will have to stay as long as you’re paying off the device. We only offer unlocked phones in our shop.
To lock a phone, the carrier adds a software code on the phone during the manufacturing phase. That limits the phone from working on another network until you enter an unlocking code. The easiest way to know if a phone is unlocked when you buy it is to look for specs clearly stating that the phone is unlocked.

GSM vs. CDMA
When you’re bringing over a phone from one carrier to another, it’s not only locked phones which limit you, unfortunately. Carriers operate under one of two types of networks: CDMA or GSM. Out of the four biggest carriers with their own network, AT&T and T-Mobile run on GSM, while Sprint and Verizon Wireless use CDMA. All other carriers operate one of these four networks (except for US Cellular who has its own network). You can check with your carrier which network you’re on if you’re uncertain. US Mobile is a GSM carrier.
In general, an unlocked GSM phone from AT&T and T-Mobile will work on each other’s networks. If you have a locked device, your carrier can unlock it if you meet their individual criteria.
Older phones from Verizon and Sprint, on the CDMA network, don’t operate with a SIM card. That basically means that those phones are restricted and can’t be used on other CDMA networks. However, most, if not all, 4G LTE devices from Verizon and Sprint are technically capable of operating on a GSM network, as LTE needs a SIM card to operate. Examples of phones compatible with all carriers 4G LTE speeds: iPhone 6, 6+, 6s, 6s+ and Google Nexus 5 models and Nexus 6 models.

Unlocked phones compatible with US Mobile
When people ask us if their phone is compatible with our network, we usually ask them these two questions:
- Does your phone have a SIM card slot? Check the back or on your phone’s sides if it has a slot for a SIM card. If yes, it’s likely GSM capable and should, therefore, work on US Mobile.
- To avoid uncertainty, check the technical specs. Either google the name of the phone or check your phone’s serial number. Your phone has a unique 15-digit code, IMEI or MEID, which can be found in the phone settings, or by entering *#06# on the dial pad.
- Is the phone unlocked? If you’re still in a contract or have outstanding payments, your phone is most likely locked to that carrier. You have a legal right to have the phone unlocked if you meet the carriers’ criteria, described further in How to Unlock Your Phone from any Carrier.
- If you happen to have a SIM card handy, you can always try to pop it into the phone to see if it’s unlocked or not.
- If your phone isn’t unlocked, we can help you unlock it. All you need to do is to fill out this Unlock Request.
We hope that this sheds some light on how to bring your own device (BYOD) to another network. Feel free to add comments and questions in case we need to clarify things further!
Phone Compatibiliy
If I buy a blue studio view XL unlocked 5.7 smartphone can you make phone call and play game and music on it
You can use this phone on our GSM LTE network (white SIM card) for calls, texting and cellular data. Gaming and music should be just fine too.
I have a lg x charge that takes a sim card it was on xfinity mobile i payed for a unlock code it said it was successful i can 0ut my us cellular sim in no ptoblem but i get no service dies this mean the unlock code did not work
Hi Melussa. We’ll be better able to help you at [email protected] with those types of questions!