Hope I'm posting this in the right place! Does the Call Me feature stay active for all Webexes or do you have to reset it in your Preferences each time you want to join a call?
Thanks for posting your question in the community! If you login to the browser version, you can update your default preferences and you are given these options. I don't believe you are able to set up Call Me as the default, but you should be able to set up a default number for your Call Me needs. You will enter the number you would like to be the default Call Me number here as well.
Hopefully this helps. If not, here are some Help Center docs that might be of help.