Problem with incoming calls (w/o ModemManager/Ofono)
#1
As the title suggests, my problem is not related to any modem management software.

The first incoming call after the modem starts up works fine.
But after that first call, regardless of whether I answer it or not, new incoming calls won't go through - They won't even do the ringing tones on the other phone that I'm calling the PinePhone with.

If I had to guess, I'd say the modem is announcing to the network that it is busy or something like that, causing it to not receive any calls, because for what it seems, the call isn't even reaching the modem. Again, I'm just guessing, I don't really know how cellular networks work.
Is there any AT command that would set/unset some busy state like that?

If not, then I was hoping somebody could test to see if you get the same results:
1. Boot an OS and stop ModemManager (I suggest using an sxmo image, not sure how easy it would be to completely stop modem management on other UIs).
2. `sudo screen /dev/ttyUSB2` (or just use atinout or minicom if you prefer)
3. Unlock the SIM (AT+CPIN=<YOUR_SIM_PIN>)
4. Give yourself a call from another phone.
5. You should hear the ringing tones on the calling side.
6. The caller's number should show on the output of "AT+CLCC"
7. Hang up
8. Repeat from step 4. Does the call go through? Can you hear the beeping on the calling side? Does it show up on "AT+CLCC"? Cause for me it doesn't ;-(
9. If everything works without a problem, try again a couple more times just to be sure. It does have some unexpected behavior for me sometimes.

My firmware revision (AT+GMR) is EG25GGBR07A08M2G
Restoring the factory defaults with "AT&F" didn't fix it
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#2
on Manjaro Plasma there is a huge problem on the communication between the modem and the Plasma, the modem works perfectly but plasma dialer stops to respond, if you are using Manjaro Plasma and you want to keep it then load another operating system on the SD and use it when you don't want to miss calls
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#3
(08-07-2021, 02:02 PM)mouffa Wrote: on Manjaro Plasma there is a huge problem on the communication between the modem and the Plasma, the modem works perfectly but plasma dialer stops to respond, if you are using Manjaro Plasma and you want to keep it then load another operating system on the SD and use it when you don't want to miss calls

Hi, thanks for replying,
No, I'm not using plasma. I'm using something similar to sxmo.
As I stated, my problem is not related to any modem management software.
I am interacting with the modem through serial using AT commands. There is no other program interfering.
I tried it both on arch and pmOS (sxmo), and I got the same problem.

I haven't tested it on any user-friendly mobile UI, but even if it does work there, I'd still like to know why this happens when not running modem management software, and if there are any solutions.
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#4
I doubt you are not using any modem software, you can read my thread on the hardware interface of the modem, the communication is complex, you get a signal at ring indicator pin and the voice data pass through the pcm interface to the sound module and then to ALSA

you definitely need the eg25-manager too for the power except if you do it totally manually with the gpio pins

I agree that regardless all these the calls should show up in the terminal but again maybe something interferes, it would be a good idea to try another OS for the same behaviour

I had uploaded an extensive AT manual but someone removed it
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#5
(08-07-2021, 03:00 PM)mouffa Wrote: I doubt you are not using any modem software, you can read my thread on the hardware interface of the modem, the communication is complex, you get a signal at ring indicator pin and the voice data pass through the pcm interface to the sound module and then to ALSA

you definitely need the eg25-manager too for the power except if you do it totally manually with the gpio pins

I agree that regardless all these the calls should show up in the terminal but again maybe something interferes, it would be a good idea to try another OS for the same behaviour

I had uploaded an extensive AT manual but someone removed it

You're right, I'm using software to manage modem power and all that stuff, I was just trying to avoid typing "ModemManager / Ofono / any other alternative that I've never heard of", but thanks for pointing that out.
I tried both arch and pmOS (arch barebones with dwm and my own scripts, pmOS with sxmo, ModemManager disabled). The problem occurs on both.
And at least on arch, it also happens with ModemManager, the reason I removed it was to make sure it wasn't the cause of the problem.

I tried downgrading eg25-manager on arch, since it used to work properly (or maybe I just had't noticed it this whole time). The problem still occurs.


I don't know how much you know about how a phone call works behind the scenes, but do you know what tells the caller phone to start the beeping?
Does it ping my modem and the modem pings it back?
Does the cell network know if my modem is ready to receive a call and transmits that to the caller?
Are the tones sent to it the same way voice is?

What I'm basically asking is:
The silence on the caller side (no beeping tones), is it because the call gets to my modem and it just ignores it? Or is it because it sees my modem as busy somewhere in the network and doesn't bother reaching it?

Sorry if I'm saying complete nonsense, I'm just trying to understand where exactly the cause of the problem is.

PS:
Apparently the same happens if I call the PinePhone while it is turned off: silence, no voice saying the number is currently unavailable, and no timeout it seems.
Also the ignored calls don't cause the phone to wake up from deep-sleep.
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#6
the modem regime is the most problematic part of pinephone, most operations run inside the modem and the modem communicates with the phone, the AT commands is the deepest you can go before start playing with the firmware

the fundamentals of how the modem talks to the carrier should belong to the GSM protocol

since you don't get a busy message it means that the modem is not busy with another call but it tries to do something before dealing with the call, this happens to me regularly with other phones, that is I call and hear nothing and hang up and call again

if there is a new stable firmware you should see it in dmesg

if you are with an old motherboard version 1.1 maybe this causes the problem

as far as I know Manjaro Phosh works well with the calls, try it on an SD card to be sure that there is a problem

you may not be giving the AT commands with the right parameters and you leave the modem in an intermediate state

it is complicated so try phosh to be sure that everything is configured correctly and then you do your experiments
  Reply
#7
(08-07-2021, 04:50 PM)mouffa Wrote: the modem regime is the most problematic part of pinephone, most operations run inside the modem and the modem communicates with the phone, the AT commands is the deepest you can go before start playing with the firmware

the fundamentals of how the modem talks to the carrier should belong to the GSM protocol

Thanks for the info.

(08-07-2021, 04:50 PM)mouffa Wrote: since you don't get a busy message it means that the modem is not busy with another call but it tries to do something before dealing with the call, this happens to me regularly with other phones, that is I call and hear nothing and hang up and call again

When you say it happens to you with other phones, do you mean calling other phones from the PinePhone?
Is that a problem on the PinePhone side?
For me it's just with incoming calls, outgoing works fine even when incoming stops working.

(08-07-2021, 04:50 PM)mouffa Wrote: if you are with an old motherboard version 1.1 maybe this causes the problem

I upgraded my mainboard to 1.2b 3GB

(08-07-2021, 04:50 PM)mouffa Wrote: as far as I know Manjaro Phosh works well with the calls, try it on an SD card to be sure that there is a problem

[...]

if there is a new stable firmware you should see it in dmesg

I tried latest arch and manjaro phosh, problem is still there.
I also tried an older arch phosh image, which also had the problem. I definitely didn't have this problem before, I would have noticed it while testing my scripts, which makes me believe that it's likely a firmware bug, although I didn't find any firmware warnings on dmesg.

(I kept ModemManager and all the magic background stuff running, but I think we can agree that's not the problem, so it would be pointless to try again without it)

(08-07-2021, 04:50 PM)mouffa Wrote: you may not be giving the AT commands with the right parameters and you leave the modem in an intermediate state

I really don't think I'm missing any AT command, the problem still occurs if the only AT command I type is to unlock the SIM, then I just call it, it rings, I hangup from the phone that's calling, I call again and it doesn't ring this time.
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#8
the modem firmware can get corrupted but I would leave it for the end, have a look at my thread for the modem configuration where you can read how to enter pin, make calls and hang up with ofono through DBus using the qdbus program to see if you have the same problem, the problem could originate from some update which soon will be fixed, I don't use the device as a phone anymore to test it
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#9
I tested the phone with Manjaro Plasma, it works "good" if you set aside the usual problem with PulseAudio and the switching between the profiles which causes the phone to only show the incoming call on the screen without ringing so you have to go back to the audio settings and set the audio profile again.
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#10
Tested the latest stable Manjaro Plasma, same problem.
If it works for you, it should work for me. The fact that it doesn't means the problem is not related to any software that comes in the OS image.

Variables:
- possible hardware damage (unlikely that hardware damage could limit a specific functionality the way it's doing)
- SIM card
- carrier (the android phone that I'm using to call the PinePhone has the same carrier and no problem. If it's related to the carrier in some way, it has to be partly the phone's fault.)
- modem firmware

I'll try to change the modem firmware to either fix it or scratch it off the list.
  Reply


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