How do i access to a key programmed on a Dect 300?

[scot]

Dect 300 has 10 Keys for programming.
I 've a Dect 300 that i programmed a key it. but How do i access to a key programmed?
I define a key for 'Assistant Call' on Dect 300, How i press it?

[vad]

This key can be reached via some feature (like remote extention) or via SW (like 4980).

[Eliott]

Additional to the answer posted by vad: ... only
It's not possible to "press" the key using the handset.