pj_thread_is_registered() return true for ios main thread even before I start pjsip

[qiulang@xxxxxxxxxxxxxxx (qiulang)]

Hi,

I just found that pj_thread_is_registered() return true for ios main 
thread even before I start pjsip!

So I call following as my first function call in 
application:(UIApplication *)application 
didFinishLaunchingWithOptions:(NSDictionary *)launchOptions, i.e. before 
I start pjsip. And to my surprise it printed out Register!

  if (!pj_thread_is_registered()) NSLog(@"Not register");
  else NSLog(@"Register");

But why  is that ?

Thanks!

Qiulang