Programming switchboards: How is the “Telephone call transfer” programmed?

An incoming call to the switchboard can be transferred externally only if there are two telephone lines by programming the switchboard as follows:
1 - Program the "direct call" and "private line" functions for both lines
98 1234 61 2 5 R
98 1234 62 2 5 R

2 - Activate the function with 911 R

3 - Program quick-dial number 30
98 1234 30 yyyyyyyy R

4 - Activate the function with 961 R (960 R to deactivate).

With these switchboard settings, the telephone line is no longer engaged by pressing "0" but by pressing "20".