[aprssig] AVRS Question

[Matthew Willis]

I looked a bit for an answer to this AVRS question, but I still haven't found what I'm looking for.  (There's a song in there somewhere.)

When a user requests a QSO via AVRS, and the callee's callsign is used on an APRS digipeater, WX station, or other always-on, no message receiving capability function, how does/should AVRS determine if the callee is truly there and available for a QSO?

-lilmatt
N2PYI