The use of call data records (CDRs) to establish links between suspects is well known and understood. In a number of major enquiries in the UK, however, it was found that CDRs contained apparently erroneous or nonsensical data which prevented the use of well-established techniques based on caller IDs contained within CDRs. Further analysis suggested that some form of number “spoofing” was being used and techniques were developed to associate calls made using one of the two mechanisms which appeared to be in operation. A working hypothesis about how the calls are being handled in order to implement obfuscation has been developed, based on additional data leaked by some of the mobile network providers.

使用呼叫数据记录（CDR）在嫌疑人之间建立链接是众所周知的。然而，在英国的许多主要查询中，发现CDR包含明显错误或无意义的数据，这阻止了使用基于CDR中包含的呼叫者ID的成熟技术。进一步的分析表明，正在使用某种形式的号码“欺骗”，并且开发了一些技术来关联使用似乎正在运行的两种机制之一进行的呼叫。基于一些移动网络提供商泄漏的其他数据，已经开发出一种有效的假设，即如何处理呼叫以实现混淆。