my FP3+ is running LineageOS for microg, most recent version available (releases at 2022-10-20).
My problem is, on outgoing calls I do not get a free-line signal (“Freizeichen”), at least not when using VoLTE or Wifi calling.
Previously, I was using the Vodafone Germany network, where the free-line signal worked, but Wifi calling was not functional there.
I moved to Congstar (basically a brand of Telekom Germany) a couple of months ago (and got a brand new SIM card there). Now, both wifi calling and VoLTE work perfectly, but the free-line signal doesn’t.
If I dial an outgoing number, I just hear nothing at all, until either the other side picks up and starts talking or the call is rejected.
Out of curiosity, I forced the phone into 2G mode, placed a call and immediately got a free-line signal there, so obviously this feature is not completely broken.
What is suspect here is an issue with the phone’s (baseband?) firmware. As firmware updates are not included in Lineage for Microg, updating the phone’s firmware seems to be the most promising approach here. Unfortunately, I have absolutely no clue how to do this
So, you wizards of the Fairphone Forum, what’s the best way to update the Firmware on my handset? Is there some way to do this from recovery? Should I boot into TWRP for updating?
Best regards and thanks in advance!