Outbound caller ID number rotation and its risks

See also

Sources

1. 1
   47 CFR 64.1200(k)(3) lets a terminating provider block calls without liability when they are blocked based on reasonable analytics designed to identify unwanted calls, subject to conditions including considering caller ID authentication information, nondiscriminatory application, no line-item charge and redress.

   47 CFR 64.1200 Delivery restrictions · paragraph (k)(3) · Checked 2026-10-14
2. 2
   47 CFR 64.1200(k)(10) requires a terminating provider, on a subscriber's request and at no charge, to supply within 3 business days a list of calls to that number blocked under an analytics program in the prior 28 days.

   47 CFR 64.1200 Delivery restrictions · paragraph (k)(10) · Checked 2026-10-14
3. 3
   47 CFR 64.1200(k)(9) requires a terminating provider that blocks on the basis of analytics to immediately return SIP 603+ on IP networks or ISUP cause 21 on non-IP networks, and every provider in the call path to pass it back.

   47 CFR 64.1200 Delivery restrictions · paragraph (k)(9) · Checked 2026-10-14
4. 4
   47 CFR 64.1200(k)(8) requires a terminating provider that blocks calls to provide a single point of contact on its public-facing website for blocking complaints and to give a status update within 24 hours.

   47 CFR 64.1200 Delivery restrictions · paragraph (k)(8) · Checked 2026-10-14
5. 5
   CallHippo's Auto Rotate Number page describes assigning outbound numbers automatically from a pool of registered numbers by campaign, region and a configurable per-number daily call limit, and ties the feature to connect rates rather than to spam labels.

   Auto Rotate Number · feature description sections · Checked 2026-10-14
6. 6
   CallHippo's Auto Rotate Number page appears to have been revised after the FCC quoted it in March 2026: the FCC quoted per-call rotation wording, while the page read on 2026-10-14 describes per-number daily limits and does not clearly state a different number for every call.inferred

   Auto Rotate Number · page text compared with FCC 26-17 paragraph 53 · Checked 2026-10-14
7. 7
   47 CFR 64.1601(e) requires anyone engaged in telemarketing to transmit caller identification information that includes either CPN or ANI and, when available from the telemarketer's carrier, the telemarketer's name.

   47 CFR 64.1601 Delivery requirements and privacy restrictions · paragraphs (e) and (e)(1) · Checked 2026-10-14
8. 8
   47 CFR 64.1601(e)(1) requires that the telephone number provided as telemarketing caller ID permit any individual to make a do-not-call request during regular business hours, whether it is the calling number or a substituted seller customer service number.

   47 CFR 64.1601 Delivery requirements and privacy restrictions · paragraph (e)(1), final sentence · Checked 2026-10-14
9. 9
   47 CFR 64.1601(e)(2) prohibits any person or entity engaged in telemarketing from blocking the transmission of caller identification information.

   47 CFR 64.1601 Delivery requirements and privacy restrictions · paragraph (e)(2) · Checked 2026-10-14
10. 10
    The Free Caller Registry states that registration does not guarantee redress and that multiple submissions of the same telephone number provide no additional value.

    Free Caller Registry · registration page terms text · Checked 2026-10-14
11. 11
    The Free Caller Registry states that neither the call protection providers nor their carrier partners use registration data to deliver Caller ID Name.

    Free Caller Registry · registration page data-use statement · Checked 2026-10-14
12. 12
    The Free Caller Registry is brought to businesses by First Orion, Hiya and TNS and lets businesses register their outbound business telephone numbers at no charge.

    Free Caller Registry · page header (Brought to you by) and registration form introduction · Checked 2026-10-14
13. 13
    Free Caller Registry self-registration is limited to businesses that make calls on their own behalf; third parties registering for other businesses must contact the call protection providers directly.

    Free Caller Registry · eligibility statement on registration page · Checked 2026-10-14
14. 14
    Comments on the FCC 26-17 NPRM were due June 8 2026 and reply comments and Paperwork Reduction Act comments were due July 7 2026.

    Combatting Illegal Robocalls Through FCC Numbering Policies; Implementation of TRACED Act-Knowledge of Customers by Entities With Access to Numbering Resources · field dates; field comments_close_on · Checked 2026-10-14
15. 15
    The FCC 26-17 NPRM was published in the Federal Register on May 8 2026 at 91 FR 25312 as document 2026-09134.

    Combatting Illegal Robocalls Through FCC Numbering Policies; Implementation of TRACED Act-Knowledge of Customers by Entities With Access to Numbering Resources · fields publication_date, citation, document_number · Checked 2026-10-14
16. 16
    Genesys Cloud pre-call rules for voice campaigns include a Set Caller ID name and number action that runs before the call is placed, based on conditions such as a contact column, phone number or time.

    Pre-call rules for voice campaigns · section on pre-call rule actions · Checked 2026-10-14
17. 17
    In Genesys CX Contact, a Caller ID Set assigned to a dialing profile, campaign template or campaign group makes Outbound Contact Server select, sequentially or randomly, a different caller ID each time a given number is dialed.

    Create and Manage Caller ID Sets (CX Contact Help) · section Caller ID Set Overview · Checked 2026-10-14
18. 18
    Hiya Enterprise Caller Scoring, announced February 24 2023, assesses a calling business's reputation across all the numbers it owns so that rotating to a new number does not reset that reputation.

    Hiya Sets Out to Take Down Spam Industry · press release body, paragraphs describing Enterprise Caller Scoring · Checked 2026-10-14
19. 19
    Hiya reports that number rotation appears in more than half of the illegal robocall campaigns its honeypot of Hiya-owned numbers observes, and that over a quarter of those robocalls use one number per call.

    Number rotation undermines consumer spam protections — here's what carriers can do about it · section on honeypot findings · Checked 2026-10-14
20. 20
    Hiya warns that analytics services treat new numbers as higher spam risk and that less sophisticated services might flag every new number as spam until proven otherwise, which would penalise legitimate callers who rotate.

    Number rotation undermines consumer spam protections — here's what carriers can do about it · section A worrying trend · Checked 2026-10-14
21. 21
    Hiya estimated in February 2023 that on any given day about 30 percent of phone numbers used to make calls on mobile networks have little or no call history.

    Hiya Sets Out to Take Down Spam Industry · press release body · Checked 2026-10-14
22. 22
    Hiya reports that 31 percent of calls its users reported as unwanted used number rotation and 20 percent used a different number for every call.

    Number rotation undermines consumer spam protections — here's what carriers can do about it · section on user reports · Checked 2026-10-14
23. 23
    In a March 25 2024 ex parte letter to the FCC Wireline Competition Bureau, the National Consumer Law Center asked the FCC to use TRACED Act authority to adopt a rule that unequivocally prohibits number rotation for outbound calls, while also arguing existing regulations already prohibit it.

    Ex Parte to Wireline Bureau on Numbering Policies · resource summary page text · Checked 2026-10-14
24. 24
    FCC 26-17 asks whether the Commission should prohibit the provision of trial numbers in connection with number cycling.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 57 · Checked 2026-10-14
25. 25
    FCC 26-17 asks how number cycling should be defined so that a rule would not bar non-robocall uses, and floats indicators such as many disconnected numbers from the same blocks appearing in the Reassigned Numbers Database.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 57 · Checked 2026-10-14
26. 26
    FCC 26-17 asks whether number rotation by legitimate callers actually works, whether analytics improvements reduce the need for it, and whether its harms outweigh its benefits.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 56 · Checked 2026-10-14
27. 27
    FCC 26-17 seeks comment on whether and to what extent the Commission should develop rules prohibiting or limiting number cycling.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 56 · Checked 2026-10-14
28. 28
    FCC 26-17 asks whether wholesale providers and number resellers should share responsibility for compliance with any cycling rule and whether multiple resale layers worsen misuse.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 58 · Checked 2026-10-14
29. 29
    FCC 26-17 cites the Anti-Robocall Multistate Litigation Task Force complaint describing an operation that routed more than 4.5 billion calls in under two years using 474.8 million different telephone numbers.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 52, citing Multistate Avid Telecom Complaint at 24 para 88(a) · Checked 2026-10-14
30. 30
    FCC 26-17 reports that about 72 percent of the numbers in that operation were used for a single call, and that five other operations used between 71 and 84 percent of their numbers only once.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 52 · Checked 2026-10-14
31. 31
    FCC 26-17 says calls from cycled numbers can receive the highest STIR/SHAKEN attestation level as if they were legitimate, which makes cycling particularly troubling to the Commission.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 51, citing the NCLC and EPIC letter filed March 25 2024 at 1-2 · Checked 2026-10-14
32. 32
    FCC 26-17 describes number cycling as using a large quantity of telephone numbers, each used on a rotating basis as few as one or two times.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 51 · Checked 2026-10-14
33. 33
    FCC 26-17 states that number cycling may help callers evade call analytics that flag individual numbers.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 51 · Checked 2026-10-14
34. 34
    FCC 26-17 cites Hiya data that 18 percent of all reported unwanted calls in the United States originate from numbers with minimal call history.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 52 · Checked 2026-10-14
35. 35
    FCC 26-17 cites a 2023 Hiya survey of 300 US business leaders in which 60 percent said they rotate numbers at least multiple times a month and 29 percent change numbers automatically or daily.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 54, citing Wallace, Hiya blog, June 28 2023 · Checked 2026-10-14
36. 36
    FCC 26-17 is a Notice of Proposed Rulemaking titled Combatting Illegal Robocalls Through FCC Numbering Policies, adopted March 26 2026 and released March 27 2026 in WC Docket Nos. 26-49, 20-67, 13-97 and 07-243.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · caption and adoption/release line, page 1 · Checked 2026-10-14
37. 37
    FCC 26-17 acknowledges that there may be legitimate uses of number cycling.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 54 · Checked 2026-10-14
38. 38
    FCC 26-17 reports the NANC's observation that legitimate callers may rotate numbers because of a perception, fueled by call completion metrics, that anti-robocall analytics are mistakenly labeling or blocking their calls, and so view rotation as a warranted countermeasure.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 54, citing NANC CATA Report at 12 · Checked 2026-10-14
39. 39
    FCC 26-17 proposes no rule text banning number rotation; its cycling section only seeks comment, so the NPRM by itself creates no federal prohibition on rotating outbound caller ID numbers.inferred

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · Section V.A paragraphs 51-58 read with Appendix A proposed rules · Checked 2026-10-14
40. 40
    FCC 26-17 reasons that, given the quantity of numbering resources consumed by number cycling, deterring or eliminating cycling should also reduce demand for numbering resources.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 71 · Checked 2026-10-14
41. 41
    The proposed rule text in FCC 26-17 would require number resellers to certify that they will not use numbers they obtain to knowingly transmit, encourage, assist or facilitate illegal robocalls.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · Appendix A, proposed 47 CFR 52.15(l)(2)(A) · Checked 2026-10-14
42. 42
    FCC 26-17 states that services enabling call cycling are readily available and gives as an example a CallHippo Auto Rotate Number feature marketed to display a different number on each call.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · paragraph 53, citing callhippo.com/auto-rotate/ (last visited Mar. 24 2026) · Checked 2026-10-14
43. 43
    In FCC 26-17 the Commission seeks comment on whether or how it should address robocalling that uses number cycling, which it treats as the same practice as number rotation.

    Combatting Illegal Robocalls Through FCC Numbering Policies, Notice of Proposed Rulemaking (FCC 26-17) · Section V.A, paragraph 51 · Checked 2026-10-14
44. 44
    FCC 25-15 requires providers to stop using SIP 603, 607 and 608 to signal analytics-based blocking no later than 12 months after the order's Federal Register publication.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Eighth Report and Order (FCC 25-15) · paragraphs 15, 22 and 23; Appendix A · Checked 2026-10-14
45. 45
    FCC 25-15 requires the exclusive use of SIP code 603+ on IP networks for immediate notification of calls blocked on the basis of reasonable analytics.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Eighth Report and Order (FCC 25-15) · paragraph 15 · Checked 2026-10-14
46. 46
    FCC 25-15 declined to adopt additional protections for lawful callers against erroneous blocking beyond those already in the rules.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Eighth Report and Order (FCC 25-15) · paragraph 25 · Checked 2026-10-14
47. 47
    In FCC 25-15 the Commission agreed with consumer groups that renting DIDs so callers can pretend to be someone else for the express purpose of evading blocking and labeling is a concern that merits caution.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Eighth Report and Order (FCC 25-15) · paragraph 26, citing Joint Consumer Reply Comments at 8-9 (EPIC et al., filed Sept. 8 2023) · Checked 2026-10-14
48. 48
    For US telemarketing, every number in a rotation pool that is displayed as caller ID must itself permit a do-not-call request during business hours unless the seller's customer service number is substituted, so a pool of outbound-only numbers that cannot be called back would not satisfy 47 CFR 64.1601(e)(1).inferred

    47 CFR 64.1601 Delivery requirements and privacy restrictions · paragraph (e)(1) · Checked 2026-10-14
49. 49
    Rotation spreads volume across numbers but does not remove call-level signals the FCC lists, such as low average call duration and low completion ratios, and analytics vendors also score individual calls independent of the number, so rotation is not a reliable way to avoid analytics-based treatment.inferred

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Declaratory Ruling and Third Further Notice of Proposed Rulemaking (FCC 19-51) · paragraph 35, read with Hiya blog section on Hiya Protect layers (Spam Threat Scanning) · Checked 2026-10-14
50. 50
    FCC 19-51 gives as examples of reasonable call analytics factors large bursts of calls in a short timeframe, low average call duration, low call completion ratios, invalid numbers placing large volumes of calls, common CNAM values across providers, complaint volume, sequential dialing patterns and neighbor spoofing patterns.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Declaratory Ruling and Third Further Notice of Proposed Rulemaking (FCC 19-51) · paragraph 35 · Checked 2026-10-14
51. 51
    FCC 19-51 declared that voice service providers may offer opt-out call-blocking programs based on any reasonable analytics designed to identify unwanted calls.

    Advanced Methods to Target and Eliminate Unlawful Robocalls, Declaratory Ruling and Third Further Notice of Proposed Rulemaking (FCC 19-51) · paragraph 34 · Checked 2026-10-14
52. 52
    Rotating among numbers the caller is actually assigned is not itself named in 47 CFR 64.1604; exposure under that rule turns on whether the displayed number is misleading or inaccurate and on the intent element.inferred

    47 CFR 64.1604 Prohibition on transmission of inaccurate or misleading caller identification information · paragraph (a), read as a whole · Checked 2026-10-14
53. 53
    47 CFR 64.1604(a) prohibits any person or entity, with intent to defraud, cause harm or wrongfully obtain anything of value, from knowingly causing a caller ID service to transmit or display misleading or inaccurate caller identification information in connection with a voice or text messaging service.

    47 CFR 64.1604 Prohibition on transmission of inaccurate or misleading caller identification information · paragraph (a) · Checked 2026-10-14
54. 54
    16 CFR 310.4(a)(8) permits substituting the seller's or charity's name and its customer or donor service telephone number for the number used to place the call, provided that number is answered during regular business hours.

    16 CFR 310.4 Abusive telemarketing acts or practices (Telemarketing Sales Rule) · paragraph (a)(8), proviso · Checked 2026-10-14
55. 55
    Under the Telemarketing Sales Rule, 16 CFR 310.4(a)(8), it is an abusive practice for a seller or telemarketer to fail to transmit the telephone number, and the telemarketer's name when the carrier makes it available, to any caller identification service in use by the call recipient.

    16 CFR 310.4 Abusive telemarketing acts or practices (Telemarketing Sales Rule) · paragraph (a)(8) · Checked 2026-10-14
56. 56
    Twilio Voice Integrity submits registered US numbers to the carriers' analytics vendors TNS for Verizon, First Orion for T-Mobile and Hiya for AT&T, which review the numbers and may update how they are labeled.

    Voice Integrity · introduction · Checked 2026-10-14

Documents

Cite this page

WarmTransfer. (2026, October 14). Outbound caller ID number rotation and its risks. WarmTransfer. https://warmtransfer.net/knowledge/caller-id-number-rotation

@misc{warmtransfer-caller-id-number-rotation,
  title  = {Outbound caller ID number rotation and its risks},
  author = {{WarmTransfer}},
  year   = {2026},
  url    = {https://warmtransfer.net/knowledge/caller-id-number-rotation},
  note   = {Verified 2026-10-14}
}