code: public void setExpires(int seconds) {
  		try {
  			ExpiresHeader expiresHeader =
  				SipFactoryImpl.headerFactory.createExpiresHeader(seconds);
  			expiresHeader.setExpires(seconds);
  			this.message.setExpires(expiresHeader);
  		} catch (Exception e) {
  			throw new IllegalArgumentException("Error setting expiration header!", e);
  		}
  	}
docs: /*
  (non-Javadoc)
  @see javax.servlet.sip.SipServletMessage#setExpires(int)