Isn't calling takes 3~5sec of delay when first call?

it happen on iOS device for ios12.

Xcode log says
[reports] Main Thread Checker: UI API called on a background thread: -[UIApplication canOpenURL:]
PID: 10326, TID: 2101166, Thread name: (none), Queue

but for second try, it call directly.

I don’t think it’s problem of call number plugin because when I call with +tel:~~~ it also happened.

how can I solve this problem?