Voice doesn't have any sort of mailing list management built into it. I think adding it would be quite a lot of work - probably more than is justified given other systems like Mailchimp already exist!

(as well as a signup page, there'd need to be list management, email management, tracking who reads things, providing unsubscribe pages, meeting the various rules of the GDPR, etc)

I would recommend using something like Mailchimp, and embedding their sign up widget onto a page of your site using the Raw HTML includelet.

For example, you can see on these Voice sites a signup form embedded on a page: Merton CIL Homepage - Superhighways e-news page.

Thanks

Joe