In my experience only phone numbers and email addresses are verified, and only on initial domain registration. Post registration I get regular "ICANN verification" emails which all pretty much say to only act if there's incorrect information.

With the exception of the .nyc TLD I've been able to use a PO Box and a forwarding phone number for registrations across registrars for years. .nyc provided no way to demonstration the required NYC nexus except for the postal address to be a physical building in New York City so I let that domain lapse.