> How would you ensure there is no existing backdoor in the chip's firmware? Basically, you can't. See my other comment in this thread. If your modem is used

> How would you ensure there is no existing backdoor in the chip's firmware? Basically, you can't. See my other comment in this thread. If your modem is used in the USA (and likely elsewhere), your cell service provider won't allow it on the network unless it's running firmware that they approve of. Period. This usually means firmware blobs provided by them with absolutely no means of inspecting what it does. If it's on the network, it has a backdoor. No exceptions. This is why there are no open source modems. It's not a legal possibility.