Serial Caller

Hi Guys,

I have a serial caller who calls our tollfree line xxxx but when I check the logs the number is not showing.
how can I unmask the number or reveal the number so that I can block or prevent this from happening.
the call come through as our Outbound CallerID (Dadhi Trunk) xxxxx.

see logs below below

[2014-09-16 23:58:29] VERBOSE[30235] sig_pri.c: – Accepting call from ’ ’ to ‘xxxx’ on channel 0/20, span 3
[2014-09-16 23:58:29] VERBOSE[30235] sig_pri.c: – Accepting call from ’ ’ to ‘xxxx’ on channel 0/20, span 3

You will have to talk to your network operator. ANI is normally considered confidential information that will not be provided ordinary customers (although it might be passed to freephone services).

Thank you very much