Besides the regular iBeacon uuid, major and minor fields, (and transmission strength), the Kontakt beacons have an extra 4 letter unique ID. This is tranmitted in the [Scan Response Packet] and is seen without the need to connect to the bluetooth device when the
See here in the Kontak.io docs
(Here's a question on Stack Overflow about the definition of the Scan Response Packet) It has pointers to the definition. I presume the Kontakt unique ID is the Beacon ID field of the Scan Response Packet.
If I wish to emulate the broadcasting of a Kontakt beacon from my app on android (preferably react-native, for example using react-native-beacon-simulator), what do I need to do?