WarmTransfer
numbering identity · published

Call blocking and analytics labeling remediation

Verified 2026-09-24 · 57 sources · tier 1–3 · 1 superseded

Superseded guidance: 1 source has been superseded by newer ones.

Under 47 CFR 64.1200(k)(3), terminating voice service providers may block calls without liability using reasonable, competitively neutral analytics that consider caller ID authentication information where available, provided consumers are given sufficient information to opt out 6​41. However, providers are explicitly prohibited from blocking emergency calls placed to 911 29.

Regulatory requirements for call blocking

When a terminating provider blocks calls based on any analytics program—whether executed directly or through a third-party service—it must immediately return an appropriate response code to the call's origination point, and every voice service provider in the call path must transmit that code 38. Terminating providers must meet blocking safeguards regardless of whether they employ a third party, though providers are not responsible for blocking initiated by a service chosen directly by the consumer 47.

Under amended 64.1200(k)(9), the appropriate response code is SIP 603+ as defined in ATIS-1000099 for calls terminating on an IP network, and ISUP cause code 21 with cause location 'user' for calls terminating on a non-IP network 3. FCC 25-15 was adopted on 27 February 2025, released on 28 February 2025 in CG Docket No. 17-59, and published at 90 FR 13416 on 24 March 2025 17. The Federal Register document lists an effective date of 25 March 2026, though amendments to 47 CFR 64.1200(o) were delayed indefinitely pending notice of information-collection approval 16. Providers must implement SIP 603+ no later than 12 months following Federal Register publication (24 March 2025), and must cease using SIP 603, 607, and 608 for analytics-based blocking once 603+ is implemented and in no case later than that 12-month window 2​12.

RFC 8197 defines SIP 607 (Unwanted) as a response from the called party's user agent indicating that the offered communication is unwanted because of the caller's identity 39. RFC 8688 defines SIP 608 (Rejected) for an intermediary, such as a call analytics engine, that blocked the call; it can carry a jCard in Call-Info giving the intermediary operator's contact for redress 40. ATIS and the SIP Forum announced ATIS-1000099 on 23 August 2022 (adopted 16 August 2022) as a 603 profile signaling analytics-based blocking and identifying the blocking provider to balance caller redress against withholding feedback from malicious callers 1​7.

SIP 603+ uses the reason phrase 'Network Blocked' rather than 'Decline', along with a Reason header signaling analytics-based blocking and redress contact details 4. Bandwidth documents the Reason header as SIP cause 603 with a text parameter containing a version value, the blocking entity's identity, and a redress URL, telephone number, or email 5. Bandwidth states that from March 2026 it applies no code remapping, retries, or route advance to SIP 603 responses, passing valid reason phrases and Reason headers transparently 8.

Network interworking rules specify that when a response crosses from an IP to a non-IP network, SIP 603+ must map to ISUP code 21; from non-IP to IP, ISUP code 21 with cause location 'user' must map to SIP 603 or 603+ 24. Standard SIP 603 responses may continue where an ISUP code 21 has been translated into a standard 603 that cannot be distinguished as a 603+ 25. WarmTransfer's reading of the sources is that callers whose response crosses a TDM segment are likely to receive a plain 603 lacking redress contact details, because ISUP cause 21 carries no Reason header text, leaving the caller to identify the blocking provider through other means 43.

FCC 25-15 also requires voice service providers to block calls purporting to originate from numbers on a reasonable do-not-originate (DNO) list, warning that omitting obvious numbers that could be added with little effort may render a list unreasonable 15. Specified DNO categories include inbound-only government numbers at the government's request, inbound-only private numbers used in imposter scams at the entity's request, invalid NANP numbers, unallocated NANP numbers, and unused allocated numbers 14.

Blocking redress and dispute resolution

Any terminating provider that blocks calls under 64.1200 or uses caller ID authentication information in determining how to deliver calls must publish a single point of contact on its public-facing website for call blocking error complaints 37. The provider must resolve disputes within a reasonable time, provide a status update to the disputing party within 24 hours at minimum, and may not charge callers for reporting or resolving complaints made in good faith 42​31.

Under opt-in or opt-out analytics programs, terminating providers must provide subscribers, upon request and at no additional charge, a list of calls blocked to their number within 3 business days, including date, time, and calling number 10. FCC 20-187 limits this list to calls blocked in no fewer than 28 days before the request 11.

Call labeling mechanics and remediation

In FCC 20-187, the Commission declined to address erroneous call labeling, leaving the blocking redress mandates inapplicable to mislabeled calls 18. FCC 20-187 also excluded labeled calls from the mandatory blocked-calls list, noting that consumers receive labeled calls and can see them in their missed-call list 27. WarmTransfer's reading of the sources is that federal rules do not establish a notification code, list entry, or mandatory resolution timeline for analytics labels (such as 'Spam Likely'), leaving label remediation to carrier and analytics vendor voluntary procedures 28.

Carrier and analytics ecosystem points of contact compiled by USTelecom's Industry Traceback Group include:

  • AT&T / Hiya: att.com/reviewmycalllabel 52
  • Verizon / TNS: voicespamfeedback.com or communications@tnsi.com 52
  • T-Mobile / First Orion: callreporting.t-mobile.com 52
  • Lumen / Nomorobo: nomorobo.com/contact 52
  • Comcast Xfinity: xfinity.com/support/articles/report-call-blocking-errors or 844-963-0215 51
  • Charter / Spectrum: reportspam.spectrum.com/charter/ 51

Direct analytics portals include First Orion (calltransparency.com), Hiya (hiya.com/manageyourcallerid), TNS (reportarobocall.com/trf/), and RoboKiller exception requests (robokiller.com/request-block-list-exception) 50.

The Free Caller Registry, operated jointly by First Orion, Hiya, and TNS, allows businesses to register up to 20 US ten-digit outbound numbers without charge, with each provider acknowledging receipt separately 20. However, registration does not guarantee redress because each call protection provider conducts independent analysis 19. First Orion also provides free business number registration across major carriers collecting business name, industry, website, phone, and address, though its API access supports T-Mobile registrations only 21. Verizon states that feedback submitted via its voice spam form may not change future call labels, as data is passed to third-party analytics providers and labeling incorporates factors beyond caller ID authentication 53. TNS provides a reporting form for wrongly blocked or labeled numbers that collects company details, serving providers, call volume, and customer feedback, requiring email verification prior to submission 48. Hiya advises businesses to register numbers rather than rotating them, stating that rotating numbers reduces caller trustworthiness 23. WarmTransfer's reading of the sources is that resolving mislabeled numbers across US carriers generally requires submitting remediation requests to each analytics vendor (Hiya, TNS, and First Orion) individually 36.

In FCC 25-15, the Commission declined to require caller name display when authenticated caller ID indications are shown, encouraging ongoing development of Rich Call Data and branded calling 30. CTIA's Branded Calling ID delivers name, logo, and call reason to smartphones as Rich Call Data in cryptographically signed STIR/SHAKEN calls, utilizing vetting, onboarding, and signing agents alongside network operators 9.

In proposed rulemaking FCC 25-76 (adopted 28 October 2025; comments due 5 January 2026, reply comments due 3 February 2026), the Commission proposed requiring terminating providers to transmit verified caller identity to handsets when calls receive A-level attestation 32​33. FCC 25-76 also proposed that gateway providers mark foreign-originating calls, that intermediate providers pass this marking downstream, and that analytics engines consider foreign origination in blocking decisions 35.

UCaaS platform spam settings

In Microsoft Teams, spam filtering evaluates inbound PSTN calls and displays a 'Spam Likely' notification for suspected spam 46. Configured in calling policies and enabled by default, the setting may include basic and CAPTCHA IVR checks 46. Microsoft states that Teams spam filtering is distinct from inbound call blocking 44. Administrators configure the feature in PowerShell via the -SpamFilteringEnabledType parameter in CsTeamsCallingPolicy cmdlets, such as Set-CsTeamsCallingPolicy -Identity Global -SpamFilteringEnabledType Enabled 45.

In Webex Calling, the setting 'Block calls that failed Caller ID validation' is disabled by default 54. Webex Calling features for call indications and Caller ID settings apply only to locations in the United States and Canada 56. Webex Calling can also integrate with certified caller reputation provider Mutare for customers headquartered in North America, requiring a separate subscription to score inbound PSTN calls from 0.0 to 5.0 to block, challenge with a CAPTCHA, or allow calls 55. WarmTransfer's reading of the sources is that UCaaS spam settings govern only inbound call treatment for the tenant, without altering how external terminating carriers label outbound calls placed by that tenant 49.

See also

Applicability

Applies to: FCC 47 CFR 64.1200, FCC 20-187, FCC 25-15, IETF SIP, ATIS-1000099, Bandwidth voice network, USTelecom Industry redress contact list, First Orion Free Caller Registry, First Orion Business number registration, Verizon Voice spam feedback, TNS Robocall feedback form, Hiya spam analytics, US carrier analytics, CTIA Branded Calling ID, FCC 25-76, Microsoft Teams Phone, Cisco Webex Calling, and Webex Calling. Deployments: multi-tenant, any, and pstn. Sources checked 2026-09-24. Webex Calling call indication features and Caller ID settings apply exclusively to locations in the United States and Canada 56. Mutare caller reputation integration in Webex Calling applies only to organizations headquartered in North America 55. FCC 25-15 requirements apply to US voice service providers on the PSTN, effective 25 March 2026, with 47 CFR 64.1200(o) effectiveness delayed pending further notice 16.

What remains uncertain

Whether FCC 25-76 caller identity and foreign-call-indicator proposals were adopted in 2026 is not covered by the sources below. How CCaaS or CPaaS platforms surface SIP 603+ to tenants and dialers is not covered by the sources below. The effect of originating attestation level from UCaaS providers on terminating labels is not covered by the sources below. Whether redress under 64.1200 reaches labeling driven by caller ID authentication is not covered by the sources below. The effective status of mandatory DNO blocking at 64.1200(o) after OMB approval is not covered by the sources below. Which carriers and handsets display CTIA Branded Calling ID today is not covered by the sources below. Non-US labeling and blocking regimes, including Ofcom in the UK and CRTC in Canada, are not covered by the sources below. Handset-native labeling by Google, Apple, and Samsung and its redress channels are not covered by the sources below.

See also

Related to

  • Branded calling and CNAM delivery — Branded calling (CTIA BCID / Rich Call Data) is the display-side counterpart to label remediation; FCC 25-15 urged RCD and branded calling but declined to mandate caller name display. Proposed by this packet; no relationship was previously recorded.

Referenced by

Sources

  1. 1
    The rule defines SIP 603+ by reference to ATIS-1000099, adopted 16 August 2022.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Final rule text, amended § 64.1200(k)(9)(i) · Checked 2026-09-24
  2. 2
    FCC 25-15 required providers to implement SIP 603+ no later than 12 months after the order's Federal Register publication (24 March 2025).
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · SUMMARY / synopsis para. 15 · Checked 2026-09-24
  3. 3
    Under amended 64.1200(k)(9), the appropriate response code is SIP 603+ as defined in ATIS-1000099 for calls terminating on an IP network, and ISUP cause code 21 with cause location 'user' for calls terminating on a non-IP network.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Final rule text, amended § 64.1200(k)(9)(i)-(ii) · Checked 2026-09-24
  4. 4
    SIP 603+ differs from a standard 603 by using the reason phrase 'Network Blocked' instead of 'Decline', together with a Reason header that indicates analytics-based blocking and gives redress contact information.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Synopsis, description of SIP code 603+ · Checked 2026-09-24
  5. 5
    Bandwidth documents the 603+ Reason header as SIP cause 603 with a text parameter carrying a version value, the blocking party's identity, and a redress contact given as a URL, telephone number or email.
    SIP 603+ FAQ · FAQ: 'What does SIP 603+ look like' · Checked 2026-09-24
  6. 6
    Under 47 CFR 64.1200(k)(3) a terminating provider may block voice calls without liability when blocking uses reasonable analytics designed to identify unwanted calls, those analytics consider caller ID authentication information where available, and consumers may opt out with sufficient information to decide.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(3)(i)-(iii) · Checked 2026-09-24
  7. 7
    ATIS and the SIP Forum announced ATIS-1000099 (Robocall Call Blocking Notification) on 23 August 2022 as a 603 profile that signals analytics-based blocking and the blocking provider, balancing redress for legitimate callers against withholding feedback from malicious callers.
    ATIS/SIP Forum Innovation Delivers Robocall Call Blocking Notification Standard · Press release body, paragraphs 1-3 · Checked 2026-09-24
  8. 8
    Bandwidth states that from March 2026 it applies no code remapping, no retries or route advance, and header integrity to SIP 603 responses, passing reason phrases and Reason headers through transparently when their syntax is valid.
    SIP 603+ FAQ · FAQ: processing rules section · Checked 2026-09-24
  9. 9
    Branded Calling ID is a CTIA service delivering name, logo and call reason to smartphones as Rich Call Data in cryptographically signed calls using STIR/SHAKEN, with vetting, onboarding and signing agents and network operators as roles.
    Branded Calling ID home · Home page: overview and ecosystem roles sections · Checked 2026-09-24
  10. 10
    A terminating provider that blocks under an opt-out or opt-in analytics program must, on the subscriber's request and at no additional charge, give the subscriber within 3 business days a list of blocked calls to that number with date, time and calling number.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(10) · Checked 2026-09-24
  11. 11
    FCC 20-187 limited the blocked-calls list to calls blocked in no fewer than the 28 days before the request.
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Para. 62, Section III.C.2 · Checked 2026-09-24
  12. 12
    FCC 25-15 directs providers to stop using SIP 603, 607 and 608 for analytics-based blocking once they implement 603+, and in no case later than 12 months after Federal Register publication.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · SUMMARY; synopsis on 603+ implementation · Checked 2026-09-24
  13. 13
    When a caller makes a credible showing that its calls were erroneously blocked, the terminating provider must promptly cease the blocking.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(8) · Checked 2026-09-24
  14. 14
    The DNO list categories in FCC 25-15 are inbound-only government numbers at the government's request, inbound-only private numbers used in imposter scams at the entity's request, invalid NANP numbers, unallocated NANP numbers, and unused allocated numbers.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Synopsis, do-not-originate section · Checked 2026-09-24
  15. 15
    FCC 25-15 requires every voice service provider to block calls purporting to originate from numbers on a reasonable do-not-originate list, and warns that a list omitting obvious numbers that could be added with little effort may be deemed unreasonable.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Synopsis, do-not-originate section; amended § 64.1200(o) · Checked 2026-09-24
  16. 16
    The FCC 25-15 Federal Register document is dated effective 25 March 2026, except the amendment to 47 CFR 64.1200(o), which was delayed indefinitely pending a further Federal Register notice announcing information-collection approval.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · DATES section · Checked 2026-09-24
  17. 17
    FCC 25-15, the order requiring SIP 603+ for analytics-based blocking, was adopted 27 February 2025, released 28 February 2025 in CG Docket No. 17-59, and published at 90 FR 13416 on 24 March 2025.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Header / SUPPLEMENTARY INFORMATION · Checked 2026-09-24
  18. 18
    In FCC 20-187 the Commission expressly declined to address erroneous call labeling, so the blocking redress rules adopted there were not extended to mislabeled calls.
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Para. 49, Section III.C · Checked 2026-09-24
  19. 19
    The Free Caller Registry states that registering numbers does not guarantee redress, because each call protection provider performs its own independent analysis.
    Free Caller Registry · Registration page disclaimer · Checked 2026-09-24
  20. 20
    The Free Caller Registry is operated jointly by First Orion, Hiya and TNS. It lets a business register up to 20 US ten-digit outbound numbers at no cost, and each call protection provider acknowledges receipt separately.
    Free Caller Registry · Registration page: operator line, form sections · Checked 2026-09-24
  21. 21
    First Orion offers free business number registration that vets numbers across major carriers, collecting business name, industry, website, phone and address; its API access supports T-Mobile registrations only.
    Register Your Number · Register Your Number page: cost statement, steps, API note · Checked 2026-09-24
  22. 22
    The 2020 Fourth Report and Order (FCC 20-187) required terminating providers blocking on IP networks to return SIP 607 or 608 and ISUP code 21 on TDM networks, with compliance by 1 January 2022.
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Paras. 56 and 61, Section III.C.1 · Checked 2026-09-24
  23. 23
    Hiya advises businesses to register their numbers and discourages rotating numbers, which it says makes a caller appear less trustworthy.
    How Carriers Label Spam Calls and How Businesses Can Support a Healthy Call Reputation · Article, business recommendations section · Checked 2026-09-24
  24. 24
    When the blocking code crosses from an IP to a non-IP network, SIP 603+ must map to ISUP code 21; from non-IP to IP, ISUP code 21 with cause location 'user' must map to SIP 603 or 603+.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Final rule text, amended § 64.1200(k)(9)(iii)-(iv) · Checked 2026-09-24
  25. 25
    FCC 25-15 allows a standard SIP 603 to continue where ISUP code 21 has been translated into a standard 603 that cannot be distinguished as a 603+.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Synopsis, discussion of 603+ implementation · Checked 2026-09-24
  26. 26
    Under 64.1200(k)(11) a provider may block without offering an opt-out when reasonable analytics, including caller ID authentication information where available, show a call pattern highly likely to be illegal; the conditions include human oversight and ceasing the blocking once it knows the calls are lawful.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(11) · Checked 2026-09-24
  27. 27
    FCC 20-187 declined to include labeled calls in the blocked-calls list, reasoning that consumers receive labeled calls and can see them in their missed-call list.
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Para. 66, Section III.C.2 · Checked 2026-09-24
  28. 28
    No federal rule found in this research gives callers a notification code, list entry or fixed resolution timeline for analytics labels (such as 'Spam Likely'), as distinct from blocking; label remediation depends on each carrier's and analytics vendor's voluntary process.inferred
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Paras. 49 and 66, read with § 64.1200(k)(9) and (k)(10) · Checked 2026-09-24
  29. 29
    47 CFR 64.1200(k)(5) prohibits a provider from blocking a voice call that is an emergency call placed to 911.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(5) · Checked 2026-09-24
  30. 30
    In FCC 25-15 the Commission declined to require display of caller name information when a provider displays an indication that caller ID was authenticated, and urged industry to keep developing Rich Call Data and branded calling.
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Synopsis para. 19, 'Status of Rich Call Data or Other Caller Name Tools' · Checked 2026-09-24
  31. 31
    A terminating provider may not charge callers for reporting or resolving blocking error complaints made in good faith.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(8), final sentence · Checked 2026-09-24
  32. 32
    The FCC 25-76 NPRM (adopted 28 October 2025) proposes requiring terminating providers to transmit verified caller identity information to the handset whenever they show that a call received A-level attestation; it is a proposal, not an adopted rule.
    Advanced Methods To Target and Eliminate Robocalls (proposed rule; FCC 25-76), 90 FR 56101 · NPRM para. 8 · Checked 2026-09-24
  33. 33
    Comments on FCC 25-76 were due 5 January 2026 and reply comments 3 February 2026.
    Advanced Methods To Target and Eliminate Robocalls (proposed rule; FCC 25-76), 90 FR 56101 · DATES section · Checked 2026-09-24
  34. 34
    FCC 25-76 proposes to eliminate the rules permitting voice service providers to block calls on a do-not-originate list, as part of removing outdated blocking provisions.
    Advanced Methods To Target and Eliminate Robocalls (proposed rule; FCC 25-76), 90 FR 56101 · NPRM para. 85 · Checked 2026-09-24
  35. 35
    FCC 25-76 proposes that gateway providers mark calls originating outside the United States, that intermediate providers pass that marking downstream, and that providers using reasonable analytics to block consider foreign origin as a factor.
    Advanced Methods To Target and Eliminate Robocalls (proposed rule; FCC 25-76), 90 FR 56101 · NPRM paras. 48 and 54 · Checked 2026-09-24
  36. 36
    A number mislabeled across US carriers generally needs a remediation request with each carrier's analytics vendor (Hiya, TNS, First Orion), because each keeps its own analysis and neither the joint registry nor carrier forms guarantee label changes.inferred
    Free Caller Registry · Registration page disclaimer; read with the USTelecom contact table · Checked 2026-09-24
  37. 37
    A terminating provider that blocks calls under 64.1200 or uses caller ID authentication information in determining how to deliver calls must publish a single point of contact on its public-facing website for call blocking error complaints.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(8), first sentence · Checked 2026-09-24
  38. 38
    A terminating provider that blocks calls based on any analytics program, itself or through a third-party blocking service, must immediately return an appropriate response code to the call's origination point, and every voice service provider in the call path must transmit it.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(9), lead-in · Checked 2026-09-24
  39. 39
    RFC 8197 defines SIP 607 (Unwanted) as a response from the called party's user agent indicating that the offered communication is unwanted because of the caller's identity.
    RFC 8197: A SIP Response Code for Unwanted Calls · Section 4 · Checked 2026-09-24
  40. 40
    RFC 8688 defines SIP 608 (Rejected) for an intermediary, such as a call analytics engine, that blocked the call; it can carry a jCard in Call-Info giving the intermediary operator's contact for redress.
    RFC 8688: A Session Initiation Protocol (SIP) Response Code for Rejected Calls · Section 1 and jCard/Call-Info section · Checked 2026-09-24
  41. 41
    The 64.1200(k)(3) analytics safe harbor also requires that all analytics be applied in a non-discriminatory, competitively neutral manner.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(3)(iv) · Checked 2026-09-24
  42. 42
    The terminating provider must resolve blocking disputes within a reasonable time and must at minimum give the disputing party a status update within 24 hours.
    47 CFR § 64.1200 - Delivery restrictions · § 64.1200(k)(8), second sentence · Checked 2026-09-24
  43. 43
    When a blocked call's response crosses a TDM segment, the caller is likely to receive a plain 603 without the 603+ redress contact, because ISUP cause 21 carries no Reason-header text; the caller then has to identify the blocking provider some other way.inferred
    Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416 · Amended § 64.1200(k)(9)(iii)-(iv); synopsis on ISUP 21 translation exception · Checked 2026-09-24
  44. 44
    Microsoft states that Teams spam filtering is not the same as blocking inbound calls, which is a separate feature.
    Configure spam filtering for calls in Microsoft Teams · Intro, second paragraph · Checked 2026-09-24
  45. 45
    Teams spam filtering is configured in PowerShell with the -SpamFilteringEnabledType parameter of the CsTeamsCallingPolicy cmdlets, for example Set-CsTeamsCallingPolicy -Identity Global -SpamFilteringEnabledType Enabled.
    Configure spam filtering for calls in Microsoft Teams · Section 'Using PowerShell' · Checked 2026-09-24
  46. 46
    Microsoft Teams spam filtering, set in calling policy and on by default, checks inbound PSTN calls and shows the user a 'Spam Likely' notification for suspected spam; the On setting may include basic and CAPTCHA IVR checks.
    Configure spam filtering for calls in Microsoft Teams · Intro; 'Using the Teams admin center' step 4 · Checked 2026-09-24
  47. 47
    FCC 20-187 expects voice service providers to meet the blocking safeguards whether or not they use a third party, while a provider is not responsible for blocking by a service the consumer chose.
    Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187) · Para. 50, Section III.C · Checked 2026-09-24
  48. 48
    TNS's robocall feedback form lets businesses report numbers they believe are wrongly blocked or labeled, asking for company details, serving providers, call volume and customer feedback, and requiring email verification before submission.
    TNS Robocall Feedback · Business reporting section of the form · Checked 2026-09-24
  49. 49
    The spam settings in Webex Calling and Teams govern how the tenant's inbound calls are labeled or blocked; they do not change how terminating carriers label the tenant's outbound calls, which is decided by the called party's carrier and its analytics vendor.inferred
    Secure Calling and Spam mitigation · Whole article (inbound-only scope; no outbound labeling statements) · Checked 2026-09-24
  50. 50
    USTelecom lists analytics-company registration portals: First Orion at calltransparency.com, Hiya at hiya.com/manageyourcallerid, TNS at reportarobocall.com/trf/, and RoboKiller exception requests at robokiller.com/request-block-list-exception.
    Call Labeling and Blocking Points of Contact · Analytics companies section · Checked 2026-09-24
  51. 51
    The same USTelecom list gives Comcast Xfinity's blocking-error contact as xfinity.com/support/articles/report-call-blocking-errors or 844-963-0215, and Charter/Spectrum's as reportspam.spectrum.com/charter/.
    Call Labeling and Blocking Points of Contact · Contact table, rows Comcast, Charter · Checked 2026-09-24
  52. 52
    USTelecom's Industry Traceback Group lists labeling and blocking redress contacts by carrier: AT&T/Hiya (att.com/reviewmycalllabel), Verizon/TNS (voicespamfeedback.com or communications@tnsi.com), T-Mobile/First Orion (callreporting.t-mobile.com), and Lumen/Nomorobo (nomorobo.com/contact).
    Call Labeling and Blocking Points of Contact · Contact table, rows AT&T, Verizon, T-Mobile, Lumen · Checked 2026-09-24
  53. 53
    Verizon's voice spam feedback form states that a submission may not change how future calls are labeled; feedback goes to third-party spam analytics providers, and labeling uses factors beyond caller ID authentication.
    Verizon Voice Spam Feedback · Feedback form introductory text and disclaimer · Checked 2026-09-24
  54. 54
    The Webex Calling setting 'Block calls that failed Caller ID validation' is disabled by default.
    Secure Calling and Spam mitigation · Section 'Provision user notification using Control Hub' · Checked 2026-09-24
  55. 55
    Webex Calling can integrate a certified caller reputation provider (Mutare) that scores inbound PSTN calls from 0.0 to 5.0 and can block, CAPTCHA-challenge or allow them; it is available to customers headquartered in North America and needs a subscription with the provider.
    Secure Calling and Spam mitigation · Section 'Certified caller reputation providers with Webex Calling' · Checked 2026-09-24
  56. 56
    Webex Calling's call indication features and Caller ID settings apply only to Webex Calling locations in the United States and Canada.
    Secure Calling and Spam mitigation · Applicability note near the top of the article · Checked 2026-09-24
  57. 57
    Webex Calling maps inbound STIR/SHAKEN verstat to user-facing labels: TN-Validation-Passed with A attestation shows 'Verified Caller', TN-Validation-Failed shows 'Potential Fraud', and No-TN-Validation shows 'Possible Spam'.
    Secure Calling and Spam mitigation · Section 'Verstat value and attestation', mapping table · Checked 2026-09-24

Documents

tier 1 standards and regulators

47 CFR § 64.1200 - Delivery restrictions

Legal Information Institute, Cornell Law School (reproducing the eCFR) · 2025-08-29 · accessed 2026-09-24

tier 1 standards and regulators

Advanced Methods To Target and Eliminate Robocalls (proposed rule; FCC 25-76), 90 FR 56101

Office of the Federal Register / Federal Communications Commission · 2025-12-05 · accessed 2026-09-24

tier 1 standards and regulators

Advanced Methods To Target and Eliminate Unlawful Robocalls (final rule; FCC 25-15), 90 FR 13416

Office of the Federal Register / Federal Communications Commission · 2025-03-24 · accessed 2026-09-24

tier 1 standards and regulators

Advanced Methods to Target and Eliminate Unlawful Robocalls, Fourth Report and Order (FCC 20-187)

Federal Communications Commission · 2020-12-30 · accessed 2026-09-24

tier 1 standards and regulators

ATIS/SIP Forum Innovation Delivers Robocall Call Blocking Notification Standard

ATIS · 2022-08-23 · accessed 2026-09-24

tier 1 standards and regulators

RFC 8197: A SIP Response Code for Unwanted Calls

IETF / RFC Editor · 2017-07-01 · accessed 2026-09-24

tier 1 standards and regulators

RFC 8688: A Session Initiation Protocol (SIP) Response Code for Rejected Calls

IETF / RFC Editor · 2019-12-01 · accessed 2026-09-24

tier 2 current vendor documentation

Branded Calling ID home

CTIA / BCID · accessed 2026-09-24

tier 2 current vendor documentation

Configure spam filtering for calls in Microsoft Teams

Microsoft · 2026-04-26 · accessed 2026-09-24

tier 2 current vendor documentation

Free Caller Registry

First Orion, Hiya and TNS (joint) · accessed 2026-09-24

tier 2 current vendor documentation

Register Your Number

First Orion Corp. · accessed 2026-09-24

tier 2 current vendor documentation

Secure Calling and Spam mitigation

Cisco Systems, Inc. (help.webex.com) · 2026-09-03 · accessed 2026-09-16

tier 2 current vendor documentation

SIP 603+ FAQ

Bandwidth Inc. · 2026-08-18 · accessed 2026-09-24

tier 2 current vendor documentation

TNS Robocall Feedback

Transaction Network Services (TNS) · accessed 2026-09-24

tier 2 current vendor documentation

Verizon Voice Spam Feedback

Verizon · accessed 2026-09-24

tier 3 vendor-maintained repositories

Call Labeling and Blocking Points of Contact

USTelecom (Industry Traceback Group) · accessed 2026-09-24

tier 3 vendor-maintained repositories

How Carriers Label Spam Calls and How Businesses Can Support a Healthy Call Reputation

Hiya · 2024-07-23 · accessed 2026-09-24

Cite this page

APA

WarmTransfer. (2026, September 24). Call blocking and analytics labeling remediation. WarmTransfer. https://warmtransfer.net/knowledge/call-blocking-labeling

BibTeX

@misc{warmtransfer-call-blocking-labeling,
  title  = {Call blocking and analytics labeling remediation},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/call-blocking-labeling},
  note   = {Verified 2026-09-24}
}