回答“The phone doesn't prompt for "Network unlock code"”You can use code. You can add sim to mobile and then use code 7465625#. Now it ask for unlock code use your code.
回答“How can I unlock lg306g”You can unlock lg mobile by installing custome rom and boot loader to your lg306g. For that you need to root your lg mobile. To root lg mobile enable usb debugging under developer option. then download su super user software / rooting and install it to computer . now also install root exploit to lg mobile. now disconnect your mobile from computer. Now enter into recover mode and install superuser packer to your mobile. now reboot your mobile and your mobile is rooting. You can now install your custom rom. Secondly you should enter unlock code to your lg mobile which can be created from imei number of your lg 306g. Thirdly you can recover unlock code from your lg mobile. For that download any good root explorer software then connect your lg mobile to computer. And search l root folder for unlock bin or network lock file. Such file does not exist always it is just a tricks