I was trying to blacklist calls made from a certain number in Cambodia. The number is in the format 855nnnnnnnn. 855 is the country code.
When this call comes in, the caller presses 101 for the extension from the IVR. The call goes to voicemail because it is intentionally unanswered. When extension 101 dials *32, the system says the last caller was 102, not the incoming call from Cambodia.
I can only assume that the Cambodian carrier is sending the CID with the 1 prepended. it records it as 1855nnnnnnnn
If I enter the number manually into the blacklist module, the caller is sent to the correct destination.