The Nortel UNIStim IP Softphone 2050, IP Phone 1140E, and additional Nortel products from the IP Phone, Business Communications Manager (BCM), and other product lines, use only 65536 different values in the 32-bit ID number field of an RUDP datagram, which makes it easier for remote attackers to guess the RUDP ID and spoof messages.  NOTE: this can be leveraged for an eavesdropping attack by sending many Open Audio Stream messages.