code: public void addAcceptLanguage(Locale locale) {
  		checkCommitted();
  		AcceptLanguageHeader ach = SipFactoryImpl.headerFactory
  				.createAcceptLanguageHeader(locale);
  		message.addHeader(ach);
  
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipServletMessage#addAcceptLanguage(java.util.Locale)