Crazy thought: phone number only, then after they are in, require they enter one? If they don't set one or forget, they just get a text and reset it? The psyc

Crazy thought: phone number only, then after they are in, require they enter one? If they don't set one or forget, they just get a text and reset it? The psychology of this is interesting because on one hand they might feel less safe but on the other they might not care and just want to jump right in!