PBX and Voicemail Hacking

A PBX, or Private Branch Exchange, is a telephone switch usually located on your premises. It provides communications between individual users and the public switched telephone network. A PBX is often paired with a voicemail messaging system. A PBX or voicemail hack occurs when hackers discover a hole in the security of the telephone system. The hackers take advantage of that hole by generating calls that they have no intention of paying for. Instead, calls are billed to the organization using the PBX or voicemail system. 

What can you do to protect your business?

  • Contact your equipment vendor immediately and have a proactive discussion on PBX and voicemail security.
  • Deactivate unused features and mailboxes.
  • Change default passwords for users and administrators and increase the length of passwords.
  • Restrict login attempts.
  • Restrict message notification or out-dialing on voicemail boxes.
  • Block operator services or international access as appropriate.
  • Block casual dialing from the PBX: 101XXXX and 1010XXX.
  • Add verified account codes for international dialing.
  • Review the call detail on monthly invoices and report anything suspicious.
  • Invest in call accounting software or station message detail recording to review internal extensions for abnormal activity.
  • Do not allow remote access until confident it is secure. 

Do you have VoIP equipment?

If your customer premises equipment is improperly configured, it is possible that unregulated inbound SIP traffic will pass through your IP network / PBX and out of your SIP trunk group. This can allow Internet-based hackers access to local dial tone from the IP PBX / SIP trunk group without your knowledge.

  • Contact your equipment vendor about running a security audit of your IP and voicemail systems.
  • Check the status of your firewall and/or other call processing software for errors or manipulation of setup.
  • Verify the configuration of your IP PBX to ensure that WAN traffic is isolated from SIP Trunk solution.
  • Block Internet WAN traffic from accessing the gateway via SIP (Port 5060) for TCP and UDP.

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