WordPress Membership Plugin
Yep, Biz account.
Currently using Sandbox mode for this site, and after setting phone as a required field in the main settings https://www.paypal.com/businessmanage/preferences/website it does appear as required, but testing the contents of $ipn_data at around line 134 in /simple-membership/ipn/swpm_handle_subsc_ipn.php nothing is there for phone so I’m thinking it must be something that needs setting in the button settings submitted to paypal, since it is not using a button defined in the paypal account.