Dial customer on alternate number

Imagine you are calling a person and you are asked if you can call back on another number. How do you do that?

1. Enter the number in the Telephone2 field and move the cursor to another field (at that moment the value is saved in the Telephone2 field)
2. Check the 'Dial alternate numbers' checkbox
3. Hang up

As soon as you hang up, the 'Number options' button turns red. Press to call Phone2.