Slashdot | Net2phone Sues Skype
: "'Net2phone is suing Skype for patent infringement, arguing Skype violated patent 6,108,704 for 'the exchange of IP addresses between processing units in order to establish a direct communications link between the devices via the Internet.''"
Text from the patent.
"A point-to-point Internet protocol exchanges Internet Protocol (IP) addresses between processing units to establish a point-to-point communication link between the processing units through the Internet. A first point-to-point Internet protocol includes the steps of (a) storing in a database a respective IP address of a set of processing units that have an on-line status with respect to the Internet; (b) transmitting a query from a first processing unit to a connection server to determine the on-line status of a second processing unit; and (c) retrieving the IP address of the second unit from the database using the connection server, in response to the determination of a positive on-line status of the second processing unit, for establishing a point-to-point communication link between the first and second processing units through the Internet."
Hmmm.. it seems that net2phone can sue a whole lot of im clients for patent infringement and violation of patent 6,108,704
. All of them use similar method to detect user presense and initiating conversations.