Xiaomi
Mobile Data on Secondary SIM During VoLTE Calls auf Xiaomi
On a Xiaomi phone with MIUI, mobile data traffic normally follows whichever SIM is placed in a VoLTE call. If that SIM has no data plan or a weak signal, apps stall until the call ends.
MIUI includes a switch that lets the secondary SIM keep handling mobile data even while the primary SIM is busy with a VoLTE call. This avoids the interruption without forcing you to end the call first.
To turn it on or off:
Open the Settings ➔ Tap on SIM cards & mobile networks ➔ Enable or disable Use mobile data during VoLTE calls on the secondary SIM ➔ Confirm with OK
Enable this if you regularly browse, stream, or receive messages while talking and your secondary SIM has an active data plan. Leave it disabled if your secondary SIM has no data allowance, since the phone will still try to route traffic through it and may fail silently.
This setting only affects VoLTE calls. Regular voice calls over the mobile network are not affected, since they do not compete with data on the same channel the same way.