Possible hacking attempts

General Help
1

Hi all,
My phone lines are continually called by an automated system that seems to simply dial “9” for up to 6 minutes, then hangs up. On my IVRs, 9 is a language change, so the caller swaps IVRs continuously. I recently changed the IVR so that a second attempt to switch language is met with a hangup, but that does not seem to discourage them.

Lastly, the “caller” seems to be blocking caller ID (see log snippet below), so I can’t simply block the number. Over the course of a weekend, these calls can number up to 150. I have even logged a few occurances where the “caller” ties up two of my FXOs at the same time.

My questions:

  1. Has anyone else had this occur to them? Any idea what it is? My suspicion is that they are trying to obtain an outside line.
  2. Is there anything I can do to block this without affecting other calls?

[2013-04-29 08:26:23] VERBOSE[13851] sig_analog.c: – Starting simple switch on ‘DAHDI/4-1’
[2013-04-29 08:26:24] DEBUG[13851] chan_dahdi.c: CallerID number: (null), name: (null), flags=6
[2013-04-29 08:26:24] VERBOSE[13851] pbx.c: – Executing [s@from-zaptel:1] NoOp(“DAHDI/4-1”, "Entering from-dahdi with DID == ") in new stack

2

If these calls are coming directly in on your PSTN lines as your post suggests, then it is unlikely a hacking attempt. To could turn on “Privacy manager” on your inbound route perhaps.

3

If these are really “nuisance calls”, then call your provider and complain, you might not have access to the underlying CID, but they do.