Z3 D6603 GSM connection acting up

A friend of mine has a Z3 which was working fine for about half year, then started acting weird.

The issue is quite simple: the phone loses GSM connection and switches to "Emergency calls only" mode. Doing a soft reset (vol up + power) often helps, and he gets mobile network for maybe a day or two.

I've tried debugging it, but no mention of any RIL issue in logcat or dmesg. There are a few errors, but they happen when RIL is working fine too.

I installed CM12.1, and it's the same, except I can't get any signal, at all.


Has anyone ran into this issue before?

Android device acting weird, "no such file..." (Rooted)

Hello,

To start off with, I'd like to say that I'm just getting into these things, I'm semi-experienced with GSM and the signalling system, SS7. I just got my Android device(HTC One M7) yesterday, and I've been playing around with GSM, sniffing and so on, but.. You may already have guessed that I'm looking for the Kc(the ciphering key from the SIM) to decrypt my traffic.

I have tried to do it by sending AT commands, but my device is acting really weird as the title says, whenever I try to contact/access /dev/smd0, but it "doesn't exist" - That's what I get as a reply. I tried to list files in /dev/, I see them all, and I tried to getprop rild.libargs, this is the output:

root@m7:/ # getprop rild.libargs
-d /dev/smd0
root@m7:/ # echo -c "AT\r\n" > /dev/smd0
tmp-mksh: can't create /dev/smd0: No such file or directory
1|root@m7:/ #

I've tried searching on Google multiple times to 6 am, I didn't find any answers to the issue.

If anyone can help me with this issue, I'd be more than happy to give a reward, since my interest in getting this working is extreme.

Thank you.