This module splices into the macro-dialout-trunk context which might be useful for you:
I see you’re reusing the returnhere channel var from the blacklist module, it might be wise to change the name to something different in your module.
There appears to be a recentish realization that the name “blacklist” is culturally insensitive, and should be renamed to “BlockList”. That being the case, if there is not already a corresponding preferred name for whitelist, I suggest ‘AllowList’, with the added benefit that they will be listed together alphabetically. I would only just rename the GUI elements without changing the underlying rawname/code.