I'm not sure about McDonald's Italy system, but one that's frequently used in places with low/expensive cellular signal, and/or a big number of small transactio

I'm not sure about McDonald's Italy system, but one that's frequently used in places with low/expensive cellular signal, and/or a big number of small transactions, used deferred debit. Basically, it consists of updating the system every certain period of time, with the list of the revoked numbers, and assuming that the rest are cleared by default. Then, every time the process runs, it submits the transactions while obtaining the revocation list. This makes every transaction as fast as a look up on a local database table, and it is for example how it works at certain toll booths in Spain.