[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] 45apples:
i have an i747m phone on rogers network (locked). it is still on original firmware version, although it is rooted.

i recently flashed lineageos.

since then the sim card is not recognised (no network). i am unsure what the issue IS, but i have been further educating myself for the last four days on this topic and am still unclear on some things. i wonder if you could answer some questions and give a bit of guidance.

here's what i know:

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made nandroid backup before upgrading to lineageos

phone worked fine before the update to lineageos

android version was 4.0.4

the bootloader and modem has not to my knowledge been changed since purchase -- i am the original owner.

the phone was rooted shortly after purchase by me

baseband is I747MVLLE8

bootloader is i747MVLALE8

os is now lineageos 14.1-20170828-nightly-d2att

### i can receive calls. phone does not ring, but there is visual notification and i can answer and talk.

### (update) i reinstalled lineageos and now incoming DOES ring. on the screen it says "incoming call via emergency network". i do not see any way to answer the call now, and even after hanging up the initiating call it continues to ring until reboot.

### (update2) i have been able to answer the "incoming call via emergency network" and it seems to connect normally. is this a glitch, or are "incoming emergency calls" a "thing"?

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i read that one of the likely reasons is "out of date baseband/modem/bootloader"

here's what i am unsure of:

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probable cause of "no sim"

should i upgrade bootloader? if so to what version and how?

should i upgrade modem? if so to what version and how?

anything else that should be updated?

what does "d2att" stand for and represent? is it part of the hardware/model of the phone? e.g. what is the difference between d2att and d2can?

is d2att the correct "thing" for the rogers network in canada for an i747m?

can i use heimdall and the images from sammobile.com to upgrade ONLY the modem and/or bootloader? if so, what files do i use (which one's are which?)?

if i use heimdall to flash the WHOLE sammobile "firmware" what happens? do i need to flash them all incrementally (v4.1, v4.2, v4.3 etc), or can i go from 4.0.4 straight to 4.4.2?

what is the minimum baseband/modem/bootloader that will work with lineageos 14.1 (android 7?)?

what are the drawbacks associated with upgrading the baseband/modem/firmware?

should i flash an older baseband first and try to unlock my sim or is that problematic in other ways?

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i am tech savvy and can follow complex instructions. i am not afraid of SOFT bricks as long as there is some way for me to revert. what IS holding me up is the fact that there are no clear directions (that i could find so far) for doing what i am trying to do, no clear indications of what the dangers are (that i could find so far), and (seemingly) conflicting information abounds. i understand (more than ever now) that this is a very complex topic and everything in this realm is unofficial. i would be very grateful if you could bring me up to speed on this topic a bit more, help me to understand things in more depth.

my goal is to update the phone the the newest lineageos (if that is possible and recommended), and to have full functionality. IF lineageos 14.1 is not to my liking, being able to revert to SOMETHING else would be great!

thanks so much!