VoLTE, incoming call kills bluetooth connection to car kit, hangs up on caller and can't be picked by car kit at second attempt

REPRODUCIBILITY: yes
OS VERSION: 4.4.0.68
HARDWARE: X 10 III
UI LANGUAGE: german
REGRESSION: no (loosing connection to car kit), uncertain (can’t pick incoming call for socondary sim)

DESCRIPTION:

VoLTE prevents car kit to work

  • incoming call interrupts bluetooth connection if VoLTE is active and the call stops for the caller
  • after reconnection, the second sim is active for the car
  • when the caller is calling again, sim1 is then secondary sim and call can’t be picked by car kit

PRECONDITIONS:

X 10 III, sfos 4.4.0.68
dual sim scenario, sim 1 VoLTE active
car kit of Volvo V70III , supported profiles: OPP, A2DP, AVRCP, HFP, PBAP

STEPS TO REPRODUCE:

  1. for the car kit the last activated sim of the handset is active (no matter which sim is marked as active in the phone …old glitch)
  2. therefore I deactivate sim1 and activate it again after every reboot, so the active sim in the car for outgoing calls is my personal/private sim1
  3. VoLTE is active for sim1
  4. car kit connects, sim1 active for outgoing calls

EXPECTED RESULT:

incoming call for both of the sim cards can be picked by car kit (keys at the steering wheel)

ACTUAL RESULT:

  1. incoming call for sim1 kills bluetooth connection to car
  2. after reconnection sim2 is suddenly the active sim for car kit
  3. if caller is calling again on sim1 I can’t pick the call by car kit (see 4. below)

in contrast: if VoLTE is deactivated, all is good - first call can be picked

and
4. calls for the secondary sim (secondary for car kit connection - no matter which sim is marked as active in the phone) can’t be picked by car kit (only at the phone…bad idea while driving)
(scenario like in ‘STEPS TO REPRODUCE’, explititly tested even after deactivating VoLTE for sim1)

MODIFICATIONS:

none

ADDITIONAL INFORMATION:

for the issue of “can’t pick call for secondary sim by car kit” I’m not sure, if this is a regression - I did not test with old phone