I'm sending 0x10 (BART) as the first two bytes for the request new service command (I ensure that the first server doesn't support this family before issuing this request, and so far it never does) . The first server then happily replies back with the server address and auth cookie for a server that supports 0x10. <div class="gmail_quote">On Thu, Dec 9, 2010 at 1:36 PM, Mark Doliner <<a href="mailto:mark@kingant.net" target="_blank">mark@kingant.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> This problem doesn't sound familiar to me. But I wonder... when you send the SNAC with type 1 and subtype 4, what value are you sending for the first two bytes? I'm wondering if you might be sending "2," which I could imagine being problematic (i.e. you're requesting a connection of type 2 even though you already have a connection of type 2). --Mark </blockquote></div>