Telecom's DSL usage meter problems stem from a build-up of unprocessed usage data and shouldn't affect the billing system itself the telco says.
Telecom has been criticised for its usage meter – the only means for users of its JetStream DSL plans to track their usage and keep tabs on the monthly cost of the service – for being out of action on several occasions.
Telecom has always said that such outages do not affect the billing system, and now it has explained how the system works for the first time.
Telecom uses one of the world's most widely used telco billing systems, IAF Horizon from US-company Amdocs. The usage meter hangs off the side of the billing system and draws data from it for the end user.
"The usage meter is a reporting tool which takes information from the … system, but operates separately from that process. The usage amounts shown on the meter fluctuate during the overnight processing of usage records," says Telecom's external public relations firm The Presence in a written statement.
"When the meter has fluctuated during the day it is because, occasionally, overnight processing has run into normal business hours. If this happens Telecom puts up a warning message on the usage meter. It is important to note that no billing takes place until all processing is complete."
Telecom has never had an external audit of its DSL billing system, however in October last year it reviewed its billing process "from customer through to the usage meter" to ensure it recorded usage levels accurately.
"In addition, the process is tested every time there is a software upgrade to ensure it is recording accurately", says the statement.
The Horizon system is customised for each client depending on its operating circumstances – for example, European mobile phone company O2, formerly BT Wireless, uses it for billing of its mobile client base. Horizon is designed to work with all-IP networks - Telecom plans to convert to an all-IP infrastructure in the next few years.
Telecom says there are no plans to conduct an external audit of the usage meter in the near future.