How to Unlock LG K40 Free – LM-X420MM / LMX420AS / LMX420TM / LMX420QM6

In this post, we are going to unlock LG k40 for free without paying for any unlock service or unlock code. Mine is a MetroPCS K40 with model number lmx420mm.

There are six LG K40 variants. Out of these, one is factory unlocked so no need to unlock it. It is compatible with all the major GSM and CDMA carriers in the USA.

The rest of the k40 variants are –

LG K40 AT&T lmx420as
K40 MetroPCS lmx420mm
K40 T-Mobile lmx420tm
K40 Spectrum Mobile lm420qm6
K40 US Cellular lmx420qm

The unlock method differs from carrier to carrier. Let’s start with the MetroPCS / T- mobile LG k40

1. How to unlock LG K40 for free – MetroPCS lmx420mm /T Mobile lmx420tm

LG K40 MetroPCS unlock free

A MetroPCS /T-Mobile k40 can be unlocked using the pre-installed device unlock app.

Look for the “Metro by T-Mobile” folder on the home screen.

Open the folder and select the “Device Unlock” app as shown in the above screenshot.

.how to unlock lg k40 for free

Give permission to Device Unlock app by tapping “ALLOW”

The app says “Your device is network locked at this time, which prevents it from operating with other compatible wireless networks. To enquire about your device’s unlock eligibility, please continue. Tap “CONTINUE” to proceed further.

Make sure you’re connected to the internet.  It says “Connecting to the server  Please wait”.

LG K40 lmx-420 free device unlock code

Now tap “Permanent Unlock” to unlock your K40 permanently.

The device is sending a “Permanent Unlocking” request. Wait for a few moments.

The unlock is approved.  The success message says –

“Unlock Approved: Mobile Device is permanently unlocked”. To apply these settings you must restart your device.

Tap “Restart Now” and use your K40 with any GSM carrier worldwide.

If  “device unlock” fails, then you can unlock it for free only after serving a certain period with your network provider.

MetroPCS Device Unlock Policy

lg k40 metropcs unlock lmx420mm

As per the MetroPCS unlock policy, the device must be active on the MetroPCS network for at least 180 days.

You can buy the LG K40 MetroPCS device unlock service if you wish to unlock it right away.


T-Mobile Device Unlock Policy

lg k40 t-mobile unlock lmx420tm

In the case of T-Mobile LG K40. You can unlock it in 40 days if yours is a postpaid account. The serving period is 1 year for prepaid accounts.


You can also purchase an app unlock service to unlock your LG K40 T-Mobile without serving the unlock period.

2. How to Unlock LG K40 AT&T for Free – LMX420AS

LG K40 AT&T Unlock lmx420as

You can unlock your LG K40 using the official AT&T device unlock service – Visit

You can submit your IMEI over there. If your AT&T LG K40 is “unlock compatible” you’ll receive the unlock code over email.

If your device is ineligible for free unlock then you need to purchase the unlock code. You can buy the LG K40 att unlock code from here. It costs around $10

3. How to unlock LG K40 Spectrum Mobile for Free – LMX420QM6

LG K40 Spectrum Mobile Unlock lmx420qm6

To unlock K40 Spectrum Mobile for free, your device must be active on Spectrum Mobile Network for 60 days.

After serving this period, you can contact the Spectrum Mobile customer care to place an unlock request.

4. How to Unlock LG 40 US Cellular – LMX420QM


LG K40 US Cellular Unlock lmx420qm

As per the US Cellular policy, all their 4G LTE devices are sold in an unlocked state.

Insert a SIM from some other wireless network to check the unlock status of your LG K40 US Cellular Smartphone.


Please share your outcome using the below comment box. Feedback is welcome.








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