Telecom Decision CRTC 2015-432

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Ottawa, 21 September 2015

File number: 8621-C12-01/08

CISC Network Working Group – Consensus report on recommendations to deal with telephony denial of service attacks against public safety answering points


  1. Effective access to emergency services is critical to the health and safety of citizens, and is an important part of ensuring that Canadians have access to a world-class communication system.
  2. Following incidents reported internationally of telephony denial of service (TDoS) attacksFootnote 1 on the administrative telephone lines of public safety answering points (PSAPs),Footnote 2 the CRTC Interconnection Steering Committee’s (CISC) Emergency Services Working Group (ESWG) proactively requested that the CISC Network Working Group (NTWG) provide recommendations on how to prevent, detect, and stop possible TDoS attacks on PSAPs in Canada. Administrative telephone lines are used for non-emergency purposes, and are not used to receive 9-1-1 calls.
  3. On 19 March 2015, the NTWG submitted the following consensus report (the Report) for Commission approval:
    • Telephony Denial of Service attacks against PSAPs, 5 March 2015 (NTRE054)
  4. The Report can be found under the “Reports” section of the NTWG page, which is available under the CISC section of the Commission’s website at

Commission’s analysis and determinations

  1. The NTWG’s examination of possible TDoS attacks on PSAPs and its recommendations are timely and proactive, since no such attacks have been reported in Canada. Of particular note is the finding that core 9-1-1 networks in Canada are currently protected from possible TDoS attacks, and that there are safeguards and best practices already in place that mitigate risks to 9-1-1 lines.
  2. Furthermore, the Report’s recommended best practices for PSAPs and 9-1-1 network providersFootnote 3 would mitigate the risk of TDoS attacks on PSAP administrative lines, and would further enhance the existing safeguards for 9-1-1 lines.
  3. As well, the recommended development of new best practices and guidelines for the coordination between PSAPs and telecommunications service providers would provide guidance to PSAPs regarding actions and procedures they could undertake before, during, and after a TDoS attack.
  4. The Commission has reviewed and approves all recommendations in the Report.
  5. Accordingly, the Commission

Secretary General


Footnote 1

These attacks occur when malicious software is installed on a computer or other device with Internet access. The software uses a voice over Internet Protocol application to flood a telephone line with inbound calls.

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Footnote 2

PSAPs are 9-1-1 call centres established and managed by provincial/territorial or municipal governments to answer 9-1-1 calls and then dispatch the appropriate emergency responders, i.e. police, fire, or ambulance.

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Footnote 3

9-1-1 network providers supply network access to PSAPs to other carriers and to their own customers when they make a 9-1-1 call. They are incumbent local exchange carriers (ILECs) and small ILECs.

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