App store said that our app MUST use IAP for person to person servises because they are not "real-time":
Regarding guideline 3.1.1, we continued to notice that the not in real time consults in the app can be purchased in the app using payment mechanisms other than in-app purchase.
In our app we allow user to ask a question and get an answer from our expert (real person) with non-IAP payment mechanism. Expert may answer some time later (for example in an hour) so this seems as non-real-time communication with user.
How "non-real-time" feature makes a person-to-person service digital?
From App Store Review Guidelines:
3.1.3(d) Person-to-Person Services: If your app enables the purchase of real-time person-to-person services between two individuals (for example tutoring students, medical consultations, real estate tours, or fitness training), you may use purchase methods other than in-app purchase to collect those payments. One-to-few and one-to-many real-time services must use in-app purchase.