Session Border Controllers Explained

What is a Session Border Controller?

Session Border Controllers or SBC’s, are a security device or firewall for your phone system. You wouldn’t connect your computer to the internet without a firewall. You shouldn’t connect your phone system to the internet without an SBC.

It protects your phone system from Cyber Attacks and Toll Fraud while letting through the communications traffic you want.

An SBC allows staff to communicate from anywhere securely. In the office, out and about, on the road or working from home. It also enables deployment and integration with carriers and other vendors.

What Can Happen if I don't use a Session Border Controller?

Connecting your telephone system to the internet opens your PBX up to toll fraud scams. An unprotected phone system is open to phone scams which can end up costing money and in some cases into the tens of thousands!

Hackers gain access to your phone system via open ethernet ports. These ports are opened in your firewall so Session Initiated Protocol (SIP) trunks can register and establish phone calls.

The hacker can gain control of your phone system and make unauthorised phone calls from your telephone system.

Typically they make calls to overseas premium-rate numbers. The owner of the premium rate service gets paid, the hacker gets a cut and you pick up the tab. Others do it just for fun and the challenge.

So why is this a problem now?

With the rollout of the NBN across Australia, the PSTN and ISDN network will be decommissioned and replaced with Session Initiated Protocol (SIP) Trunks. It’s this technology that can allow malicious activity on your telephone system unless properly secured.

Below are currently proposed milestones in the decommissioning of the current ISDN network.

  • 1st January 2018 – New ISDN services are no longer available for customers who do not already have ISDN in place.
  • 30th June 2018 – Full cease on new or additional ISDN services for all customers. In other words, Telco’s aren’t accepting any new orders for ISDN.
  • June 2019 – Disconnections will commence.
  • Limit or restrict the phone numbers that can be dialled using restriction tables
  • By 2022 – All ISDN connections will be disconnected and the ISDN network decommissioned.

When connecting to the NBN, current services are converted to SIP trunks and are connected to the phone system either directly, on SIP supported systems, or via an Integrated Access Device (IAD). When connected directly, SIP Trunks should be connected via an SBC.

How do I reduce the risk of Toll Fraud?

  • Hide your PBX behind a SBC
  • Enforce complex and longer passwords
  • Only allow selected users to connect externally
  • Limit or restrict the phone numbers that can be dialled using restriction tables
  • Install NEC Toll Fraud Guard (available on SL2100 and SV9100)