Lunch Time Teaser – 07

Welcome to this month’s LTT.

The Challenge

ACME test call generators have convinced your CFO to accept a free trial of their latest product – the “mobile-mobile TCG analyzer”. Their latest product is branded mobile-mobile because it fits in to the back of a car and allows a mobile operator to test call scenarios across its network from different switch locations. The sender and receiver are housed in the same unit in the back of the car, and it streams near real-time data back to ACME’s head-office for reconciliation against a filtered feed from the billing system.

A schematic of the network diagram is shown below. It shows there are three MSCs, a mediation platform, and a combined rating and billing system. There are two suspense buckets (highlighted in red), where CDRs are dropped for reprocessing [please click on the picture to enlarge].


You receive a call from the ACME account manager alerting you to some missing test call CDRs in the feed from the billing system. The ACME TCG confirms a series of test calls were successfully made between 10.40am and 10.55am on 14 July but were not billed. The CFO asks you to investigate and to report back to him with your findings after lunch.

You have access to the following: The ACME reconciliation report, Billing suspense, Mediation suspense, and a combined MSC1-2-3 switch file.

What would be your answer to the CFO?

  • A – The missing CDRs have dropped in to the billing suspense bucket.
  • B – The missing CDRs have dropped in to the mediation suspense bucket.
  • C – There could be a hidden switch in the network, or
  • D – (A + B + C).

To receive the answer, please send an email to with LTT-07 in the heading. The next LTT will be published on Monday 19th August.

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.