Hi, On Feb 17, 2012, at 4:02 AM, Bo Shi wrote: > Sa?l, > The problem is not everyone can control the server setting. As a client developer, I want to know what is the standard action, if ice spec conflict with sip rfc, then I want to work around on client. You can't know in what twisted ways the server will mangle the message, so no matter how hard you try there will be cases when it will not work. > BTW: it seems the iptel.org behave different from opensips.org server. iptel.org can be workaround as Dmitry (MicroSIP) said, but opensips.org can not. Of course, they run different software. What Dimitry said is true if you apply the workaround to *both* endpoints, but you can't fix all devices in the world. You can try sip2sip.info (also free) no fix is needed, it just works. Regards, -- Sa?l Ibarra Corretg? AG Projects