I had a theater callback recently where I heard something surprising: "the cast list for this show will be posted on our website by such and such date." The date was within a week of the callback.
When so often we are told "thanks for coming in" and nothing further about a casting timeline, getting this level of clarity and specificity was a welcome change.
I wish that more theaters would adopt a system such as this one - a voice mailbox to call, a list on a website, maybe even on a backchannel URL if you don't want to make the info public to your patrons or the press too soon.
I know that casting folks are often too busy to contact everyone they're not using to let them know about it, but a system like this, where the company puts the info where actors have access to it, would make a big difference in terms of the watching phone screens and hitting send/receive on email that so many of us do the day or two after a callback.