Foreign characters in URL

[highender]

Hello,
if the link title has for example special german characters like ä, ö, ü, ß,
how is it possible to implement following in the detail URLs:

Title: Ähnliche Überschüße

xxx.com/aehnliche-ueberschuesse-s159.html
- at the moment it looks like:
xxx.com/ahnliche-uberschusse-s159.html

ä=ae
ö=oe
ü=ue
ß=ss - this one seems to implemented...

Many thanks for help
highender