If your customer is making a purchase of over £100 and they try to tap their credit or debit card for a contactless transaction, the Pomelo Pay app should prompt them to enter their PIN.
However, a handful of banks do not facilitate PIN transactions that are made online i.e. on a smartphone. If your customer's bank does not support online PIN entry then the transaction can be declined. If the issuing bank supports online PIN entry the app will ask them to enter their PIN.
Paying for a purchase on a smartphone POS is still a relatively new technology. As smartphone payment terminals increase in popularity, we expect all banks to allow these types of transactions in the very near future.