code: public void startNextUntriedBranch()
  	{
  		if(this.parallel) 
  			throw new IllegalStateException("This method is only for sequantial proxying");
  		
  		for(final MobicentsProxyBranch pbi: this.proxyBranches.values())
  		{			
  			// Issue http://code.google.com/p/mobicents/issues/detail?id=2461
  			// don't start the branch is it has been cancelled already
  			if(!pbi.isStarted() && !pbi.isCanceled())
  			{
  				pbi.start();
  				return;
  			}
  		}
  	}
docs: In sequential proxying get some untried branch and start it, then wait for response and repeat