Everyone in the call has a cryptographic ID that can be authenticated with a trusted authority. Your device would just ask all the others for a one time token

Everyone in the call has a cryptographic ID that can be authenticated with a trusted authority. Your device would just ask all the others for a one time token that it then submits to the ID server. The server tells you public identifier of the person associated with that token. We already have infrastructure for bus and rail tickets, for logging in to banks, tax authorities, health services, etc. in Norway and other countries that could easily be extended to cover this use case..