Hi Damien, I accidentally lost my copy of this thread, so had to take this copy from your archives. Thank you for your recommendation. I looked at the internet interfaces and found the following: 1 - In Dapper, where Ekiga continues to work efficiently: Interface address - ppp0[ <a href="http://190.83.59.138">190.83.59.138</a>] 2 - In Feisty, where Ekiga will not register my account: Interface addresses - ppp0[<a href="http://190.83.59.120">190.83.59.120</a>] - eth1:avahi[ <a href="http://169.254.7.219">169.254.7.219</a>] - eth2:avahi[<a href="http://169.254.8.201"> 169.254.8.201</a>] You will note that I have 3 ethernet cards: eth0 (ppp0) is the original card integrated with the IBM motherboard of my computer, which is not compatible with linux and is DE-ACTIVATED, but strangely is the selected interface in Dapper where Ekiga functions. eth1 and eth2 are each separate, linux compatible ethernet cards plugged into the PCI Bus of the computer. In Feisty, I have selected each card in turn, plugging the ISP cable into the selected card, (I do not have a router), and tried forcing Ekiga to register. Ekiga returned "Registration failed" in all attempts. For general internet connection in Firefox, I normally use eth1 for Dapper and eth2 for Feisty, because I encountered problems when trying to use eth1 for both systems. (Frequent crashes, etc.). Both function well. In Feisty, in the GUI - Preferences, I tried to edit the ppp0 code string to make it equal to that in Dapper, but found I could not do it. None of the normal methods functioned. I assume that editing has to be done via the command line. So, if your diagnosis results in a need for editing the interface addresses, please spell out the commands which I need to use. One other question: what is this "avahi"? I request your kind help in resolving this seemingly intractable problem. Regards, Ian Murdoch.