Allowing WhatsApp/SMS delivery of post links?

Hi, new to Ghost and hoping someone has some ideas about a workaround for me.

I want to be able to allow people to have a delivery option of a link via SMS/WhatsApp. At this point I don’t even know how/if I can collect phone numbers at registration (optional) as Ghost doesn’t seem to permit adding new fields.

(I am using the pro version as I am not very technically skilled)

Any thoughts on a solution within Ghost or a way to connect to an external solution with Zapier for example?

Thanks!

#help

Whoa…should have added that I am doing a paid site so there needs to be kind of reflection or member status (free/paid) in terms of who would receive what.