German phrase
Unter welchem ~ soll ich Sie speichern?
Meaning
What ___ should I save you under?
When to use it
It asks which name to use. This polite wording suits saving a contact.
Example dialogue
Unter welchem Namen soll ich Sie speichern?
What name should I save you under?
Dann unter Müller, bitte.
Then under Müller, please.