code: public void addParameterableHeader(String name, Parameterable param,
  			boolean first) {
  		if(logger.isDebugEnabled()) {
  			logger.debug("addParameterableHeader - name=" + name + ", param=" + param + ", first=" + first);
  		}
  
  		checkCommitted();
  		try {
  			String hName = getFullHeaderName(name);
  
  			if (logger.isDebugEnabled())
  				logger.debug("Adding parametrable header under name [" + hName
  						+ "] as first [" + first + "] value [" + param + "]");
  
  			String body = param.toString();
  
  			String nameToAdd = getCorrectHeaderName(hName);
  
  			Header header = SipFactoryImpl.headerFactory.createHeader(nameToAdd,
  					body);
  			if (first)
  				this.message.addFirst(header);
  			else
  				this.message.addLast(header);
  		} catch (Exception ex) {
  			throw new IllegalArgumentException("Illegal args supplied", ex);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipServletMessage#addParameterableHeader(java.lang.String, javax.servlet.sip.Parameterable, boolean)