The device number forms part of the channel ID and can be requested from the device once you are connected. It does not need to be transmitted in a data page.
i.e.
1) display wildcards the device number & transmission pattern
2) display connects to first device it finds with matching device type -> the display's ANT radio now knows the channel ID of the device it is connected to
3) the display's firmware requests the channel ID from the ANT radio which contains the device number.
This is the most basic pairing mechanism, although there are several variations that are better suited for different situations. More info is here:
