A problem with getting an answer to that is that most people have email
accounts for a long time and won't remember what info was required when
they signed up and it may have changed since then. You might get lucky
and someone who doesn't have a phone can tell you what email they use.
Hard to imagine living without any phone today. If you want low cost
VOIP, Ooma is only ~$5 a month, unlimited calls. it's "free', the $5 is
regulatory fees, taxes, etc. You do have to buy
the VOIP box, which you can find on Ebay used for less than $50, used,
last time I looked.