If there isn't an option to deactivate e one sin in your device I can not see a
When you ask l to make call does say from sim one or slow two if it does I must be remembering the number . This is a bit of a palm you could try a new second SIM as the can cause problems and you won't lose any data .check your settings in the phone app Dr any were else were you can edit call settings
DRUID DOODE
