code: public void setCharacterEncoding(String enc) {		
  		try {			
  			this.message.setContentEncoding(SipFactoryImpl.headerFactory
  					.createContentEncodingHeader(enc));
  		} catch (Exception ex) {
  			throw new IllegalArgumentException("Encoding " + enc + " not valid", ex);
  		}
  
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.ServletResponse#setCharacterEncoding(java.lang.String)