Flashing custom "unlock firmware" is a legacy hacking technique best reserved for hardware enthusiasts who understand the risks of corrupting the device's bootloader. Given the decline of 3G infrastructure, extensive modification of this hardware is rarely worth the risk of damaging the device.
The client was grateful for John's expertise and quick turnaround. As it turned out, the surplus modems were originally locked to a specific network, but with John's help, they were now free to use on any network. John, on the other hand, had expanded his knowledge of Huawei modems and had a good story to share with his colleagues. Huawei E173u-1 Unlock Firmware