This NEXUS standard application provides a prepaid telephony service, mainly intended for international traffic, where a tariff may be offered that is more convenient than that of the subscriber’s local operator.

On receiving an incoming call, where the number called is identified as associated with the "Prepaid telephone services" application, the system sends the caller subscriber a presentation message, followed by a request to dial the subscriber’s prepaid card number.

At this point, NEXUS interrogates its database, checking that the number dialled is correct and how much credit is remaining.

The caller is informed of the credit remaining and asked to dial the telephone number required; the NEXUS system performs rerouting to the destination number and, on answer, counts the cost of the call according to parameters that are settable.

If the cost of the call outstrips the remaining credit during the call, the connection is dropped and the calling party is informed through a voice message and asked to hang up.

At the end of the call, the cost is subtracted from the remaining credit on the card and this information is stored in the NEXUS database.

The cost of the call is calculated on the basis of the following:

	Calling party location (determined from the telephone number received by the NEXUS system when the call is made)
	Called party location (determined by analyzing the called party number)
	Current time band
	Card serial number (different charge profiles may be managed for different card types).

Using the previous 3 elements, the following parameters are determined:

	Fixed on-answer cost
	Variable cost depending on time (counted in seconds).