Device check
Will This Phone Work on My Line?
Check a phone before you swap it, and find out whether the swap will change your plan. Then text, email or print the answer for whoever you are helping.
Managed by M. Curtis McCoy · Last reviewed September 21, 2026 · How we make money
Free tool
Check the phone, then check the plan
Two questions. You get a plain answer you can send to somebody else.
1. Which carrier is the phone number on?
230 US carriers and the three nationwide networks.
2. Which phone are you putting on it?
Paste the IMEI if you have it. Dial *#06# on the phone to see it. If you do not have the phone in front of you, answer the question underneath instead.
Phone model (optional)
Only used on the printout and the message you send. It does not change the answer.
How old is the phone?
Phones that no longer work on any US network
Two whole categories of phone are finished in the United States, and no carrier can activate them no matter who you talk to.
- Anything 3G-only. AT&T began shutting down 3G in February 2022. T-Mobile shut down Sprint’s 3G CDMA network on 31 March 2022 and its own 3G UMTS network on 1 July 2022. Verizon finished its 3G shutdown on 31 December 2022. T-Mobile’s last 2G GSM network went dark on 3 August 2026.
- 4G phones without VoLTE. This is the one that catches people. The FCC names them specifically: a phone can show 4G or LTE for data and still be unable to place a call, because calling now runs over LTE rather than the old 3G voice channel. A 4G badge on the box is not enough.
If a phone falls into either group it will not activate, it cannot call 911, and there is no workaround. The only fix is a different phone.
How to tell whether a phone supports VoLTE
On an iPhone, open Settings, then Cellular, then Cellular Data Options. If there is a Voice & Data entry with an LTE or 5G option, the phone supports it.
On Android, open Settings, then Network & internet, then SIMs, and look for a VoLTE or Voice over LTE switch. Manufacturers name it differently, so it may sit under Mobile network or Calls.
If you cannot find the setting, do not guess. Run the IMEI through the carrier the line is on. Their approved-device list is the only answer that counts, and it gives one of four answers: fully compatible, partially compatible, incompatible, or blocked.
Finding the IMEI
Dial *#06# on the phone and it appears immediately. It is also in Settings under General and About on an iPhone, under About phone on Android, and printed on the SIM tray of most older devices.
The tool above checks the IMEI’s built-in check digit, which catches a mistyped or invented number before you hand it to a carrier. It does not identify the model, and it deliberately does not pretend to — the approved-device list belongs to the carrier and changes without notice.
Will swapping the device change my plan?
Normally, no. Moving a different phone onto a line you already have is a device change, not a plan change, and the carriers’ own support pages do not say otherwise.
The exception is the one that costs people money. If the plan on that line is not compatible with the new device, the carrier will require a plan change to complete the swap — and it will be presented as part of the same flow, with a checkbox acknowledging that changes take effect today.
That exception hits hardest on old plans. A grandfathered consumer or business plan usually cannot be restored once it comes off the line. There is no undo.
So check the number before you submit. The review screen shows a monthly cost. Compare it to the plan charge for that line on your current bill. If the two match, the plan is not changing. If they do not match, stop.
If they do not match, do not try to fix it in the app. Call the carrier and say this:
I want to change the device on this line. I do not want any change to my plan. Please confirm my plan code and monthly rate will be identical after the swap, and note that confirmation on the account.
Doing the swap without losing anything
- Check the phone first. If it is 3G-only or has no VoLTE, stop here. Nothing else matters.
- Screenshot the review screen before you submit anything.
- Compare the monthly cost on that screen to the plan charge on your bill.
- Submit only if the numbers match. If they do not, call instead and use the wording above.
- Do not cancel anything. A device swap never requires cancelling a line, and cancelling is not reversible.
If the new phone has no SIM tray
US models of the iPhone 14 and later ship with no physical SIM slot at all. There is no card to move across, so the carrier has to set up an eSIM, either through the online device-change flow or on the phone with you. That is normal and it is not a sign that anything has gone wrong.
Common questions
My phone says 4G. Why will it not activate?
Because 4G data and 4G calling are different things. Without VoLTE the phone can load a web page and still be unable to dial. The FCC lists these devices alongside 3G-only phones.
Can I just move the SIM card across?
Sometimes. If both phones take the same SIM size, both are unlocked, and the new phone is compatible, a SIM swap often works with no account change at all. It will not work if the new phone is eSIM-only.
Will I lose my number?
No. A device swap does not touch the number. Porting moves a number between carriers; this does not.
Does an unlocked phone always work?
No. Unlocked means no carrier lock. It says nothing about which radio bands the phone has or whether the carrier has approved it.
After the swap
If the phone will not work on that network, the useful next question is which network the carrier actually uses, and whether a different carrier on a different network is the better move.
Which network does your carrier use · Account number and transfer PIN · All free tools