Skip to content
Communications systems
ASD ISMISM-0549

ASD ISM 0549 Separate video conferencing and IP telephony traffic from other data

What it says

Video conferencing and IP telephony traffic is physically or logically separated from other data traffic.

Quoted as published. Everything else on this page is written by Control Stack.

What it means

In plain English

Keep video conferencing and internet phone (IP telephony) traffic separated, either by physical cabling or by logical network controls, from your normal data traffic.

This control says your video calls and internet-based phone calls (IP telephony, meaning phone calls carried over your computer network rather than a traditional phone line) should travel on their own part of the network, kept apart from your everyday data like emails, files and web browsing. You can do this physically (separate cables and equipment) or logically (using network settings such as a separate virtual network). Separating this traffic protects call quality and stops a problem on one part of the network from spilling over and exposing or disrupting your calls.

Why it matters

If video and IP telephone traffic shares the same network as general data, a breach or overload on the data network can intercept, degrade or knock out calls, and vice versa.

How to implement

  1. The IT team should set up a separate virtual network, called a VLAN (virtual local area network, a way to split one physical network into isolated logical sections), and place all video conferencing and IP telephony devices on it so their traffic does not mix with general data traffic.

  2. The IT team or network provider should configure the network switches and routers so that traffic from phones and video units is tagged and routed on its own segment, and confirm general computers cannot reach the voice and video segment without authorisation.

  3. The business owner or office manager should ask the supplier who installed the phone or video system to confirm in writing whether the separation is physical (its own cabling and hardware) or logical (separate VLAN), and keep that confirmation on file.

  4. The IT team should apply traffic priority settings, known as Quality of Service, on the separated voice and video network so calls stay clear and uninterrupted even when the data network is busy.

  5. The IT team should document the network design in a simple diagram showing the voice and video segment kept apart from the data segment, and review it whenever new phones, video units or network equipment are added.

Keep it running

Re-check the separation whenever phones, video units or network hardware are added or replaced, and confirm new devices land on the correct voice/video segment rather than the data network.

Evidence and audit

  1. Check 1 of 5What an auditor asks for

    Ask for

    a current network diagram and the configuration of the switches or routers.

    Look at

    whether video conferencing and IP telephony devices sit on a separate segment or VLAN from general computers.

    Good evidence

    shows a clearly labelled voice/video segment distinct from the data network.

  2. Check 2 of 5What an auditor asks for

    Ask for

    how the separation is achieved, physically or logically.

    Look at

    cabling records or VLAN configuration files.

    Good evidence

    names the specific method (for example, dedicated cabling, or a named VLAN with its ID) rather than a vague claim that traffic is 'kept apart'.

  3. Check 3 of 5What an auditor asks for

    Ask for

    to see the access rules between the voice/video segment and the data segment.

    Look at

    firewall or switch rules that control traffic between them.

    Good evidence

    shows that general data devices cannot freely reach the voice and video network without explicit, authorised rules.

  4. Check 4 of 5What an auditor asks for

    Ask for

    evidence that the separation is tested or verified.

    Look at

    network scans, port tests or a supplier's commissioning report.

    Good evidence

    includes a dated test result confirming the segments are isolated as designed.

  5. Check 5 of 5What an auditor asks for

    Ask for

    how the design is kept current when equipment changes.

    Look at

    change records and an updated diagram.

    Good evidence

    shows the diagram and configuration were reviewed after the most recent phone, video or network change.

Mappings

Closest match in ISO/IEC 27001: A.8.22, Network segregation for security, which this control partially meets.

ISO 27001

ISO/IEC 27001: 1 mapping

  • A.8.22Network segregation for securityPartially meets

Mappings show how controls relate across frameworks. They do not imply full equivalence or certification.