Number shows "reserved" instead of "active"

Symptom: Your new phone number appears with the status “reserved” and a deadline notice.

Cause: German telecommunications law requires verified customer data (Bestandsdaten) before a phone number can be permanently assigned.

Solution: Open Settings → Customer data (the Phone numbers page links straight to it) and fill in the short form. The number is activated in full immediately; calls also work during the deadline period.