Ding isn't the only way you can practice your ringing online. The other site which has been set up recently is Ringing Room.
As with Ding, this has been created as a response to the lack of ringing at present. However it is different to Ding in a number of ways. It runs in a web browser, so there is nothing to download. However, it has no equivalent to Bob, so you need a band in order to be able to use it.