Network connection error after call

Bug Reports
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#1

REPRODUCIBILITY (% or how often): 99%
BUILD ID = OS VERSION (Settings > About product): 3.4 and 4
HARDWARE (Jolla1, Tablet, XA2,…): x10+
UI LANGUAGE: german
REGRESSION: (compared to previous public release: Yes, No, ?): ?

DESCRIPTION:

after almost every call, i get network connection error for est. 10 seconds.

PRECONDITIONS:

operator o2 in germany

STEPS TO REPRODUCE:

  1. make a call
  2. end it
  3. wait for the connection to reestablish

EXPECTED RESULT:

no network connection error

ACTUAL RESULT:

network connection error

ADDITIONAL INFORMATION:

(Please ALWAYS attach relevant data such as logs, screenshots, etc…)

#2

Which connection type do you use? 2G, 3G, 4G?

IIRC with 2G you can only have voice or data, not both.
In my case I usually only have 2G enabled and I see this error too after making a phone call.
I am using Vodafone in the Netherlands through a reseller (HollandsNieuwe).

#3

Germany has bad 3G+ coverage compared to other “developed” countries, I’d suspect the same reason for this.

#4

Even if it was the case, why would it result in that message?
But it is not the case (at least not in general):

My semi-professional guess is that the phone is booted off the network and told to reconnect in LTE when you hang up.
…and that takes a little bit of time, and the interaction between the modem and ofono can’t quite convey that this is normal behaviour. I see this too sometimes.

And what do i mean with “booted off” - i mean release with redirect. As this is not based on measurement reports, the mapping of coverage areas is approximate, and could end up having your phone look for an LTE cell that is not strong enough. Not sure what this looks like from GSM/2G (and too lazy to look at the spec) so basing this off UMTS/3G - there is bound to be something similar.

@mankir
What technology shows when you are in the call, and where do you end up afterwards?
(And do you have a lower preference than LTE in settings?)

#5

3g only is not working anymore, so i use 4g which is degraded to 2g sometimes but not often…

#6

And as there is no VoLTE support, you would always be on 2G during calls then.
So i think the network throws you out, back to LTE, when you hang up - possibly with the wrong parameters.

So what might Jolla be able to do about it? Possibly detect it and/or suppress the error message, not much more probably.

#7

I think there is something for Jolla to investigate. I suggest this Audible tone after ignoring call is related. MEO(Altice) in Portugal…
A test call went from 4G to 3G during the call and afterwards back to 4G, but this call, with no error…