Payter Fundamental Payment Models

Payter terminals are designed above all to be reliable, flexible and functional. Whilst most payments fit into one of the three models described below, integrators should not hesitate to contact us if they have requirements which do not seem to match these modes.

Terminology

The differences between these models are predominantly the timing of Authorization and Completion messages, as well as whether or not Pre-Authorization and Incremental Authorization are used. All of these terms are defined fully in our Payment Industry Glossary.

This documentation uses the term Vend to universally depict the supply of goods or services and not necessarily to refer only to Vending Machines.

Single Step

Authorization and Completion are performed at the same time. This is the same in most retail solutions such as those in stores. It should be used where the vending or supply of the service is assured such as forecourt services, amusements, charitable donations, and some simpler vending services.

Dual Step

Authorization is completed to begin the vend, and Completion takes place only when vending of goods or services is complete. This split allows for a feedback mechanism to confirm a successful vend, and is used in many modern vending machines as standard, as well as in ticket and coffee vending where consumables are required. Should a vend be unsuccessful, the authorization can then be reversed.

Variable Multi Step

Pre-Authorization is completed to begin the vend, and Incremental Authorization is optionally used to increase the amount that is Authorized, in scenarios where the exact amount cannot be accurately determined in advance. Examples include the vending of liquid products by the litre, electricity by the kWh (for EV charging) or for a “Smart Fridge” scenario where the user is free to select one or more products from an open fridge after the initial pre-authorisation stage provides access.

When the final vend total is known, then Completion takes place. Prior to Completion, an Update is requested to match the Authorized total to the final total. This adjustment can be a Decrement, reducing the amount Authorized, or an Increment, increasing the amount Authorized.

In the diagram below, “Increment” is used as this is the most common, but this may be a “Decrement” if the requested Update is lower than the existing amount.

Increments provide flexibility. In the diagram below, they are intended to top up, potentially several times, to ensure the vend amount is always under the current authorised amount. Integrators should never allow the vend amount to exceed the current authorised amount. Payter recommend that Integrators speak to their Implementation Consultant for advice on how to use increments effectively.

Payter use “Completion”, also known as a “Commit”, to determine the final amount. If the Integrator chooses to commit (request Completion) for an amount greater than is already Authorized, there is RISK that the final amount is later rejected by the card Issuer or Acquirer resulting in a total loss.

Incremental Authorization is therefore strongly recommended when using the Variable Payment model.

Incremental Authorization is only available on the Apollo family of terminals and is not supported by all Acquirers.