Quicksearch number in phonebook

[Fuur]

Hi Yealink.

We have a problem with quicksearch that i cant really wrap my head around.

Example.

We have these 3 contacts:
Pia Klavsen
Klaus Jensen
Klaus Søndergaard

If i search 55287 for (Klaus / Klavs) these are the results:
Pia Klavsen
Klaus Jensen

However Klaus Søndergaard is not found, neither if i press the arrow down button.

If i search for "Klaus" in text these are the results:
Klaus Jensen
Klaus Søndergaard

Can you help me how to fix this for our customer?