function CheckRASConnections: string;
const
     MaxEntries = 100;
var
     BufSize: Integer;
     NumEntries: Integer;
     Entries: array[1..MaxEntries] of TRasConn;
begin
     Entries[1].dwSize := SizeOf(TRasConn);
     Bufsize := SizeOf(TRasConn) * MaxEntries;
     RasEnumConnections(@Entries[1], BufSize, NumEntries);
     if numentries > 0 then
       result := strpas(@Entries[1].szEntryName)
     else
       Result := 'Disconnected';
end;

//Пример использования:

ShowMessage(CheckRASConnections);