require the phone number if you must (for DOS protection - people can always use services like sms4sats), but please make the whole orderbook available upon registration. you’re obstructing access to the whole extent of the very marketplace you’ve built, in the name of a faint (and flawed) notion of trust that ultimately nobody really cares about. having to share the full list of contacts with you only to gain access to a fraction of the offers - and only to be able to say: “look! this offer is from a total stranger who for whatever reason is among the contacts of one of the gazillion people who for whatever reason are among my contacts!” - doesn’t make any sense. let me trade with everyone, and let me keep my list of contacts private.