Lunch Time Teaser – 03

Welcome to this month’s lunch time teaser; A practical RA problem, which is solvable within a 30 minute lunch break.

The Challenge

You work for a mobile network operator that offers post-pay voice services. A high-level control reconciliation performed by the billing team between the post-pay and the interconnect billing system, (shown red in the simplified network schematic below), highlighted some unexpected anomolies. The CFO is concerned there may be some revenue leakage and asks you to investigate further. He needs an answer within 30 minutes because he has been summoned to an urgent board meeting to explain the recent decline in revenue.

Unfortunately, both the post-pay and interconnect billing systems are down due to an essential IT upgrade, however, CDR data is available from MSC1, MSC2, and also from the interconnect I/C Gateway.

The interconnect billing system rates both inbound and outbound calls for integrity.


From the data you have available, what in the network is most likely to be causing the recent decline in revenue?

A – MSC 1

B – MSC 2

C – MSC1 & MSC 2

D – Interconnect I/C gateway

E – All three switches

Please email your answer to [email protected].

The answer will be revealed in two weeks time, along with the names of the first 3 correct answers.

Lee Scargall
Lee Scargall
Lee is a senior risk management professional. He has extensive experience of managing both ERM and RAFM teams in telcos around the world, having worked for Ooredoo Group, Cable & Wireless and T‑Mobile UK.

Lee earned a PhD in Electrical and Electronic Engineering from the University of Newcastle upon Tyne, UK, for advanced research in to 3G video-telephony.