Troubleshooting voice QoS markings that are stripped or ignored

See also

Sources

1. 1
   The Apple Cisco Fastlane MDM payload offers disabling Fastlane, allowing all apps to use QoS marking, or allowing only approved apps for audio and video calls.

   Cisco Fastlane device management settings for Apple devices · Settings table · Checked 2026-10-02
2. 2
   Cisco QoS Fastlane is supported on Apple devices running iOS 10, iPadOS 13.1, macOS 10.13, visionOS 1.1 or later, deployed through a configuration profile naming the business apps to prioritise.

   Cisco network enhancements for Apple devices · QoS Fastlane section · Checked 2026-10-02
3. 3
   On Catalyst 9300 switches running IOS XE 17.15, the default trust mode for a port is DSCP-based, falling back to CoS when the incoming packet is a pure Layer 2 packet.

   Quality of Service Configuration Guide, Cisco IOS XE 17.15.x (Catalyst 9300 Switches) - Configuring QoS · Trust Behavior for Wired and Wireless Ports · Checked 2026-10-02
4. 4
   On Catalyst 9300 with the trust device command, if the connected peer does not match the trusted device type, both CoS and DSCP are set to 0 and any input policy does not take effect.

   Quality of Service Configuration Guide, Cisco IOS XE 17.15.x (Catalyst 9300 Switches) - Configuring QoS · Trust device / Auto-QoS trust discussion · Checked 2026-10-02
5. 5
   The Catalyst 9800 WLC maps DSCP 46 to 802.11 User Priority 6 (voice).

   Configure Validate and Troubleshoot Wireless QoS on 9800 WLC · DSCP to UP mapping discussion · Checked 2026-10-02
6. 6
   Catalyst 9800 Metal QoS profiles cap DSCP at 46 for Platinum, 34 for Gold, 0 for Silver and 8 for Bronze, and traffic marked above the ceiling is remarked down to it.

   Configure Validate and Troubleshoot Wireless QoS on 9800 WLC · Metal QoS section, profile table · Checked 2026-10-02
7. 7
   By default a Catalyst 9800 WLC has no Metal QoS policy applied, so traffic passes without metal-profile DSCP ceilings unless an administrator configures one.

   Configure Validate and Troubleshoot Wireless QoS on 9800 WLC · Background / Default QoS behaviour · Checked 2026-10-02
8. 8
   Starting with IOS XE 17.4 the Catalyst 9800 WLC trusts the client DSCP in the AP join profile by default (qos-map trust-dscp-upstream), preserving client DSCP upstream.

   Configure Validate and Troubleshoot Wireless QoS on 9800 WLC · AP join profile / trust DSCP section · Checked 2026-10-02
9. 9
   Cisco's 9800 QoS tech note validates markings with wired-side packet captures, over-the-air captures for UP values, and the show policy-map interface wireless client mac, show wireless client mac service-policy and show dot11 qos commands.

   Configure Validate and Troubleshoot Wireless QoS on 9800 WLC · Verify / Troubleshoot sections · Checked 2026-10-02
10. 10
    An AP or controller that uses the default precedence-based DSCP-to-UP mapping will send correctly EF-marked voice downstream in the video access category, so a correct DSCP on the wire does not guarantee voice-queue treatment over the air.inferred

    RFC 8325: Mapping Diffserv to IEEE 802.11 · Section 2.3 and Section 4.2.1 · Checked 2026-10-02
11. 11
    Seeing DSCP 0 at the far end of a call that crossed the public Internet or another provider's domain does not by itself show the near-end endpoint failed to mark; markings must be checked hop by hop starting at the sender's access port.inferred

    RFC 2474: Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers · Section 3 combined with RFC 2475 Section 2.1.2 and Microsoft Teams QoS Step 5 · Checked 2026-10-02
12. 12
    The DS field replaces the IPv4 TOS octet and the IPv6 Traffic Class octet, and six bits of it carry the DSCP that selects the per-hop behaviour at each node.

    RFC 2474: Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers · Section 3 · Checked 2026-10-02
13. 13
    RFC 2474 permits nodes to rewrite the DS field as needed to provide a desired local or end-to-end service, so a changed DSCP at a downstream hop is standards-conformant behaviour, not necessarily a fault.

    RFC 2474: Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers · Section 3 · Checked 2026-10-02
14. 14
    Packets received with an unrecognized codepoint SHOULD be forwarded as if marked for the Default (best-effort) behaviour, whose recommended codepoint is 000000.

    RFC 2474: Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers · Section 3 and Section 4.1 · Checked 2026-10-02
15. 15
    A DS ingress node must assume incoming traffic may not conform to the traffic conditioning agreement and must be prepared to enforce it according to local policy, which includes re-marking at the boundary.

    RFC 2475: An Architecture for Differentiated Services · Sections 2.1.2 and 2.3.4.2 · Checked 2026-10-02
16. 16
    RFC 2475 notes that interior DS nodes, not only boundary nodes, may perform limited traffic conditioning such as DS codepoint re-marking.

    RFC 2475: An Architecture for Differentiated Services · Section 2.1.1 · Checked 2026-10-02
17. 17
    The recommended codepoint for the Expedited Forwarding PHB is binary 101110 (decimal 46).

    RFC 3246: An Expedited Forwarding PHB (Per-Hop Behavior) · Section 2.7 · Checked 2026-10-02
18. 18
    RFC 3246 says the edge of a DS domain SHOULD strictly police EF-marked packets to a rate negotiated with the adjacent upstream domain, so EF traffic exceeding that rate can be dropped at the boundary.

    RFC 3246: An Expedited Forwarding PHB (Per-Hop Behavior) · Section 3 · Checked 2026-10-02
19. 19
    RFC 4594 assigns the Signaling service class the CS5 DSCP (101000, decimal 40).

    RFC 4594: Configuration Guidelines for DiffServ Service Classes · Section 4.2 · Checked 2026-10-02
20. 20
    RFC 4594 assigns the Telephony service class the EF DSCP (101110) with priority queuing.

    RFC 4594: Configuration Guidelines for DiffServ Service Classes · Section 4.1 · Checked 2026-10-02
21. 21
    RFC 4594 recommends that markings on packet flows from untrusted sources such as end-user devices SHOULD be verified at ingress, with policing optional for trusted sources.

    RFC 4594: Configuration Guidelines for DiffServ Service Classes · Sections 4.1, 4.2 and 4.3 (conditioning text) · Checked 2026-10-02
22. 22
    RFC 8325 says wireless APs MUST NOT derive upstream DSCP from the client's Layer 2 UP marking and RECOMMENDS passing through the Layer 3 DSCP set by the wireless host.

    RFC 8325: Mapping Diffserv to IEEE 802.11 · Section 5.2 · Checked 2026-10-02
23. 23
    Under the default 802.11 mapping that takes the top three DSCP bits as the User Priority, EF (101110) maps to UP 5 and lands in the Video access category (AC_VI) instead of the Voice access category (AC_VO).

    RFC 8325: Mapping Diffserv to IEEE 802.11 · Section 2.3 and Section 4.2.1 · Checked 2026-10-02
24. 24
    RFC 8325 recommends a non-default DSCP-to-UP mapping in which EF is mapped to UP 6.

    RFC 8325: Mapping Diffserv to IEEE 802.11 · Section 4.2.1 · Checked 2026-10-02
25. 25
    Microsoft recommends network QoS policies for Teams match the client source ports with source and destination IP address any, so both incoming and outgoing media on the internal network are caught.

    Implement Quality of Service in Microsoft Teams · Step 4. Implement QoS settings, Important note · Checked 2026-10-02
26. 26
    In the Teams admin center, selecting Automatically use any available ports uses ports 1024-65535, and Microsoft says not to select it unless you are not implementing QoS.

    Configure QoS settings in the Teams admin center · Manage QoS markers in the Microsoft Teams admin center, Important note on port ranges · Checked 2026-10-02
27. 27
    Microsoft's recommended initial Teams QoS configuration marks audio with DSCP 46 (EF) on client source ports 50000-50019.

    Implement Quality of Service in Microsoft Teams · Step 3. Choose initial port ranges for each media type, table · Checked 2026-10-02
28. 28
    Teams browser-based clients continue to use dynamic ports, so port-range QoS policies targeting the Teams source ranges do not match their media.

    Implement Quality of Service in Microsoft Teams · Step 3, first bullet after the port table · Checked 2026-10-02
29. 29
    Enabling Teams QoS tags only packets leaving the client endpoint; Microsoft recommends applying matching QoS rules on all internal network devices for incoming traffic.

    Configure QoS settings in the Teams admin center · Manage QoS markers in the Microsoft Teams admin center, Important note under step 3 · Checked 2026-10-02
30. 30
    New Policy-based QoS GPOs for Teams do not take effect until Group Policy refreshes on the client; gpupdate /force run as administrator forces an immediate refresh.

    Implement Quality of Service (QoS) in Microsoft Teams desktop clients on Windows · Configuring DSCP markings using Group Policy, closing paragraph · Checked 2026-10-02
31. 31
    To verify an applied Teams QoS GPO, Microsoft says to check gpresult /R or /H output for the GPO under Applied Group Policy Objects and then inspect HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\QoS for the Application Name, DSCP Value and Local Port entries.

    Implement Quality of Service (QoS) in Microsoft Teams desktop clients on Windows · Verify DSCP markings in the Group Policy object, steps 1-5 and Table 2 · Checked 2026-10-02
32. 32
    The Intune Teams QoS configuration profile is a device policy, so its assignment groups must contain Windows devices rather than user accounts.

    Implement Quality of Service (QoS) in Microsoft Teams desktop clients on Windows · Configuring DSCP markings using Intune, step 9 · Checked 2026-10-02
33. 33
    Teams Mac and mobile (iOS and Android) clients use hard-coded DSCP values, EF for audio and AF41 for both video and screen sharing, which are not configurable.

    Implement Quality of Service in Microsoft Teams · Step 3 bullet list and Step 4. Implement QoS settings · Checked 2026-10-02
34. 34
    Microsoft describes port-based DSCP tagging on routers as working across Windows, Mac and Linux but marking traffic only from the WAN edge, not all the way to the client machine.

    Implement Quality of Service in Microsoft Teams · Step 2, Port-based tagging at router · Checked 2026-10-02
35. 35
    Teams calling and meeting signaling uses DSCP 40 (CS5) on UDP source ports 50070-50089, and those ports are not currently configurable.

    Implement Quality of Service in Microsoft Teams · Step 3. Choose initial port ranges for each media type, table and footnote · Checked 2026-10-02
36. 36
    The Teams QoS markers toggle is under Teams admin center > Meetings > Meeting settings > Network, where you can turn markers on or off but cannot set custom markers per traffic type.

    Configure QoS settings in the Teams admin center · Manage QoS markers in the Microsoft Teams admin center, steps 2-3 · Checked 2026-10-02
37. 37
    For Teams Mac, mobile and Teams Phone device markings to function, QoS must be enabled globally in the Teams admin center with the Insert Quality of Service (QoS) markers for real-time media traffic setting.

    Implement Quality of Service in Microsoft Teams · Step 4. Implement QoS settings · Checked 2026-10-02
38. 38
    Microsoft states the DSCP value must be present at both ends of a call for QoS to be effective, and recommends capturing Teams traffic at the network egress point, for example using switch or router port mirroring, to confirm it is not changed or stripped.

    Implement Quality of Service in Microsoft Teams · Step 5. Validate your QoS implementation · Checked 2026-10-02
39. 39
    Microsoft's recommended Teams QoS table marks video DSCP 34 (AF41) on ports 50020-50039 and application/screen sharing DSCP 18 (AF21) on ports 50040-50059.

    Implement Quality of Service in Microsoft Teams · Step 3. Choose initial port ranges for each media type, table · Checked 2026-10-02
40. 40
    Microsoft states QoS works as expected only when implemented on all links between callers; for remote users it can prioritize only within the internal managed network, and Microsoft recommends avoiding real-time Teams traffic over VPN.

    Implement Quality of Service in Microsoft Teams · Step 1, VPN considerations · Checked 2026-10-02
41. 41
    Teams desktop clients on Windows get DSCP markings from an OS policy: the Intune NetworkQoSPolicy CSP, the New-NetQosPolicy PowerShell cmdlet, or Group Policy Policy-based QoS, each matching the executable ms-teams.exe and the source port range.

    Implement Quality of Service (QoS) in Microsoft Teams desktop clients on Windows · Sections Configuring DSCP markings using Intune / PowerShell commands / Group Policy · Checked 2026-10-02
42. 42
    Cisco TAC states that by default Windows sets the DSCP to 0 unless an application is configured to mark its own traffic.

    Enable DSCP QoS Tagging on Windows Machines · Introduction / Background · Checked 2026-10-02
43. 43
    Cisco's Windows DSCP tech note has administrators create a DWORD named Do not use NLA with value 1 under HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\QoS and reboot before configuring Policy-based QoS.

    Enable DSCP QoS Tagging on Windows Machines · Configure, Step 1 (registry) · Checked 2026-10-02
44. 44
    Cisco's tech note says that if applications such as Jabber or Webex set their own DSCP, the Policy-based QoS advanced setting DSCP marking override can be set to Allowed so policy values do not override application markings.

    Enable DSCP QoS Tagging on Windows Machines · Configure, Step 2, Advanced QoS Settings · Checked 2026-10-02
45. 45
    Windows Policy-based QoS applies a DSCP value from 0 to 63 into the IPv4 TOS field or the IPv6 Traffic Class field of outbound traffic, matched by application path, addresses, protocol and ports.

    Quality of Service (QoS) Policy · Define QoS Priority Through a DSCP; Use QoS Policy to Apply DSCP Values and Throttle Rates · Checked 2026-10-02
46. 46
    Windows QoS Policy is not enabled by default; no QoS policies exist until an administrator creates them.

    QoS frequently asked questions · FAQ: Is QoS Policy enabled by default? · Checked 2026-10-02
47. 47
    When several Windows QoS policies apply, the more specific one wins, and at equal specificity a user-level policy takes precedence over a computer-level policy.

    QoS frequently asked questions · FAQ: What happens if conflicting QoS policies are deployed to the same computer? · Checked 2026-10-02
48. 48
    Windows QoS policies affect only the outbound traffic of the computer they are applied to; to affect traffic in both directions between two computers, policies must be applied to both.

    QoS frequently asked questions · FAQ: Do QoS policies apply to the sender or receiver of traffic? · Checked 2026-10-02
49. 49
    Wireshark exposes the IPv4 DSCP as the display filter field ip.dsfield.dscp, alongside ip.dsfield and ip.dsfield.ecn, so ip.dsfield.dscp == 46 isolates EF-marked packets in a capture.

    Wireshark Display Filter Reference: Internet Protocol Version 4 · Field table rows ip.dsfield, ip.dsfield.dscp, ip.dsfield.ecn · Checked 2026-10-02
50. 50
    A network QoS policy that classifies voice only by DSCP EF (46) will not place Zoom audio at its default marking of 56 in the EF priority queue unless the policy also matches 56 or the Zoom values are changed to 46.inferred

    Using QoS DSCP Marking · Default values combined with RFC 4594 Section 4.1 · Checked 2026-10-02
51. 51
    Zoom's default DSCP marking values are 56 for audio, 40 for video and 40 for screen sharing.

    Using QoS DSCP Marking · Overview / default values · Checked 2026-10-02
52. 52
    Zoom warns that DSCP tags may not be recognised by other internal network components and can be stripped when traversing the Internet.

    Using DSCP Marking with Zoom · Using DSCP Marking with Zoom, considerations · Checked 2026-10-02
53. 53
    Enabling Zoom DSCP marking through the web portal or Group Policy marks only packets outbound from Zoom apps; inbound prioritisation needs network-side tagging on firewalls and routers.

    Using DSCP Marking with Zoom · Using DSCP Marking with Zoom, introductory section · Checked 2026-10-02
54. 54
    When DSCP marking is enabled in the Zoom web portal, Zoom Workplace desktop and mobile apps version 6.0 or later and supported Cisco, Poly and Yealink IP phones mark Zoom Phone audio packets.

    Using DSCP Marking with Zoom · Zoom Phone section · Checked 2026-10-02
55. 55
    On Windows, Zoom desktop and Zoom Rooms need administrative privileges to apply DSCP marking, or the organisation can deploy Group Policy QoS policies matching Zoom.exe or ZoomRooms.exe with Independent Data Ports enabled.

    Using QoS DSCP Marking · Prerequisites / Windows section · Checked 2026-10-02

Documents

Cite this page

WarmTransfer. (2026, October 2). Troubleshooting voice QoS markings that are stripped or ignored. WarmTransfer. https://warmtransfer.net/knowledge/voice-qos-troubleshooting

@misc{warmtransfer-voice-qos-troubleshooting,
  title  = {Troubleshooting voice QoS markings that are stripped or ignored},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/voice-qos-troubleshooting},
  note   = {Verified 2026-10-02}
}