Can you explain “unlock” “jailbreak” “custom ROM” etc? And how to do it?

Question

These terms are thrown around by power users in all the phone forums and this forum is no exception.

It's rarer to find an explanation of what the various terms signify. Do "jailbreak" "unlock", "developer unlock" and "install a customer ROM" all mean the same thing?

If not, what do these terms mean and how do they vary?

And if they do mean the same thing, how do you "unlock" your phone for advanced tweaking?

Since "unlocking" or "jailbreaking" your phone is often part of an answer here, especially when a Windows Phone feature needs tweaking, it would be great if a power user could explain the procedure in terms a novice user can understand.

Answer 1

Phones are often "locked" in some way to stop behaviour that is not intended for general use by one of the phone manufacturer, phone operating system manufacturer or phone network.

Often the actions that are blocked would make it almost impossible to support the device, or would jeopardise the company's business in some manner.

For example, in many regions, handsets are subsidised by the network to which you're connecting, and to encourage you to stay with them, they SIM lock your phone to only work with their network.

Another example is that on Windows Phone OS (and iOS as well), it is not possible to install applications without using the relevant store. To enable developers to properly test their applications prior to public release via the store, this restriction needs to be removed, and essentially is what developer unlocking does (amongst other things). You can probably understand that it would also be difficult to support everyone in the world if they could download and install anything, as well as the security implications of virii. "Jailbreaking" is often meant as a synonym for developer unlocking.

"Unlocking" as a more general term can refer to either the removal of a SIM-lock, or developer unlocking.

Installing a custom ROM is one of the other things you can do with a developer unlocked phone, and it allows installation of an update to the operating system that is not available via the normal channels to the general public.

To developer unlock a device, the process involves setting up a developer account with Microsoft (at a cost of approx 99 USD, depending on your locale), and using the development tools from Microsoft.