VIVO Y71 QCN FIle [Network Unlock] Free Download

A QCN file, basically known as a Qualcomm Calibration Network file, is a binary file format used by Qualcomm-based mobile devices. It comprises information that is critical regarding network and radio calibration, including IMEI, RF parameters, and NV items. The information therein is quite vital in ensuring proper network connectivity to cellular, Wi-Fi, and Bluetooth functions, helping it maintain the best performance and connectivity for the device.

What are the uses?

IMEI restore: QCN files are used in cases of an invalid IMEI or after a corrupted one, especially once flashing or a firmware update has gone awry, resulting in some sort of IMEI or network problem.
Network Calibration: Due to the fact that QCN itself contains calibration data, it helps the phone maintain connectivity with the network stable and efficient, retaining vital settings related to the device in question and its requirements from the network.
Backup & Restore: QCN files can also be used to make some kind of backup from the network settings of a device. If the device loses its configuration, restoring the QCN will recover the settings automatically without going into manual recalibration of the same.
Repair & Troubleshooting: In the case of some device having weak connectivity or failing to register on any particular network, QCN files should come in handy by allowing restore or adjustment of needed network parameters. While editing the QCN files, it is always very important to save and back up the original file, lest improper modification can lead to further problems that may connect or even render your device unusable over networks.

How to restore?

Download Required Software:

Install QSPT or QPST on your computer.
Download and install UltraEdit or HxD for editing QCN files.

Obtain a Working QCN File:

Get a QCN file from a similar Vivo Y71 device that is functioning correctly. This file contains the necessary calibration data.

Edit the QCN File:

Open the obtained QCN file using UltraEdit or HxD.
Locate the IMEI section in the file (it often starts with "08 8A...").
Use an IMEI converter to input your actual IMEI number and note the output.
Replace the existing IMEI in the QCN file with the output from the IMEI converter.
Save the modified QCN file.

Connect Your Device to the Computer:

Connect your Vivo Y71 to your computer via USB.
Open QSPT or QPST and navigate to "QPST Configuration".
Check if your Qualcomm Diag port is visible (it may appear as COM9 or similar). If not, add it via Device Manager.

Restore the Modified QCN File:

In QPST, click on "Start Clients" then select "Software Download".
Check "Allow phone/file ESN mismatch".
Locate and select your modified QCN file.
Start the restoration process.

Reboot Your Device: Once the restoration is complete, reboot your Vivo Y71.
Verify Network Connectivity: After rebooting, check if your network signal has been restored and if you can make calls or use mobile data.