The sitestream.twitter.com and userstream.twitter.com clusters are intended to support only Site and User Stream calls, respectively. However, it has historically been possible to connect to public streaming endpoints, such as sample.json and filter.json, on these clusters without a problem.
The availability of these endpoints makes tuning each cluster for specific types of connections more difficult, so we will be disabling public streaming endpoints on userstream.twitter.com and sitestream.twitter.com. On userstream.twitter.com, you will only be able to connect to user.json. On sitestream.twitter.com, you will only be able to connect to site.json and the control streams endpoints. For all other streaming endpoints, please use stream.twitter.com.