Based on the CEPT recommendations T/R 61-01 and T/R 61-02, the following procedures shall apply in Liechtenstein:

• A Liechtenstein amateur radio sign call HBØ will be assigned solely to the residents with permanent address or citizens of Principality of Liechtenstein whom hold a valid CEPT / HAREC licence.
• Holders of a CEPT licence from abroad, do not need to notify the Office for Communications for the operation of radio amateur activities provided they
  use the call sign prefix HBØ/mycall.
• Holders of a HAREC licence from abroad, must apply for a permit from the Office for Communications for the operation of radio amateur activities. The
  use of call sign prefix HBØ/mycall is obligatory.
• Visitors holding a non-CEPT or non-HAREC licences are not allowed to have any amateur radio activities.

Source:
Amt für Kommunikation | Gerberweg 5 | Postfach 684 | LI-9490 Vaduz | Liechtenstein