---
title: "Rhino TAS app: Prepaid Charging Front-End"
description: A suite of voice, messaging and data control applications that authorise service access in cooperation with a real-time charging system and then meter the service usage as the prepaid balance is used. Also referred to as Online Charging Front-end, Converged pre and post-paid charging.
image: https://www.metaswitch.com/hubfs/Charts-Diagrams/rhino-tas-app-prepaid-charging-front-end.png
---

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# Rhino TAS app: Prepaid Charging Front-End

### Topics

- [Mobile](https://www.metaswitch.com/knowledge-center/reference/topic/mobile),
- [Rhino TAS](https://www.metaswitch.com/knowledge-center/reference/topic/rhino-tas),
- [Rhino TAS apps](https://www.metaswitch.com/knowledge-center/reference/topic/rhino-tas-apps)

### Developed by a Rhino TAS customer.

A suite of voice, messaging and data control applications that authorise service access in cooperation with a real-time charging system and then meter the service usage as the prepaid balance is used. Also referred to as Online Charging Front-end, Converged pre and post-paid charging.

![rhino-tas-app-prepaid-charging-front-end](https://www.metaswitch.com/hs-fs/hubfs/Charts-Diagrams/rhino-tas-app-prepaid-charging-front-end.png?width=1908&name=rhino-tas-app-prepaid-charging-front-end.png)

In recognition of the importance of real-time charging, the 3GPP now refers to "on-line" and "off-line" charging rather than "pre-" and "post-paid" charging and defines a functional separation between the charging-trigger function (CTF) of a network and the online charging system (OCS). The CTF itself is necessarily tightly-coupled with the service being delivered.

These applications can be used for both pre and post-paid subscribers in cooperation with a real-time charging system. This reduces the duplication of services and helps both retain subscribers and removes a barrier to service use.

The Online Charging Front End application combine the charging interfaces and CTF with a powerful session-control (and call-control) to deliver online charging enabled services within this new framework. This may be achieved by inserting functionality in-front of an existing service in order to generate the required charging triggers, by hosting and executing new services directly within it’s own application server environment, or via a combination of both.

Several Rhino TAS operator customers have implemented split-architecture prepaid charging systems using Rhino to deliver the call control applications. Besides the standard call, messaging and data control and metering, they have implemented:

- Prepaid balance replenishment
- Balance query by USSD and SMS
- Balance transfer
- Pay for me
- Premium content charging

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