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REVIEW 2 major objections 1 minor 113 references

Robocalls affect every continent but occur at far higher rates and cause more damage in the United States than elsewhere.

Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →

T0 review · grok-4.3

2026-07-01 04:26 UTC pith:IVGIFTG6

load-bearing objection New 65-country robocall dataset is the real output here, but the US-severity claim rests on unnormalized aggregates that the abstract does not defend. the 2 major comments →

arxiv 2606.31790 v1 pith:IVGIFTG6 submitted 2026-06-30 cs.CR

Robocalls: A Worldwide or US-only Problem? Analyzing Spam and Fraud in International Phone Calls

classification cs.CR
keywords robocallsspam callsphone fraudinternational callscall detail recordscampaign clusteringmultimodal dataset
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper gathers robocall reports and call records across 65 countries on all inhabited continents to test whether the problem is US-specific or global. It releases the first public multimodal dataset of 8.7 million call detail records plus transcripts and audio from 28 campaign clusters collected over nine months. Comparative analysis of calling patterns, co-targeting attacks, callback numbers, and language use shows robocalls operate internationally yet reach substantially greater volume and reported losses inside the US. The work supplies concrete steps for future research and remedies aimed at reducing robocall effectiveness.

Core claim

Although robocalls constitute an international problem, the severity of the threat is significantly higher in the US than in other countries.

What carries the argument

A multimodal international robocall dataset containing 8.7 million call detail records, 839 transcripts, and 677 recordings from 28 identified campaign clusters, used to compare patterns across 65 countries.

Load-bearing premise

The collected robocall reports and records from 65 countries are representative enough to support cross-country comparisons despite differences in legal systems, reporting mechanisms, and data availability.

What would settle it

Uniform measurement of robocall volume per capita in a new set of countries showing rates comparable to the United States would contradict the finding of markedly higher US severity.

Watch this falsifier — get emailed when new claim-graph text bears on it.

If this is right

  • Mitigation resources can be allocated most efficiently by treating the US as the primary target while still addressing shared international campaigns.
  • Common robocall campaigns identified across borders enable coordinated blocking of callback numbers.
  • Linguistic adaptations within the same language across regions indicate scammers tailor messages to local audiences.
  • Public release of the dataset supports development of detection tools that work beyond single-country data.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same data-collection approach could be applied to other scam vectors such as SMS or messaging apps to test whether US concentration holds there as well.
  • Differences in severity may trace to phone penetration rates or enforcement differences, suggesting targeted regulatory comparisons between the US and lower-severity nations.
  • Callback-number extraction methods described could feed into real-time reputation systems shared across carriers worldwide.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

2 major / 1 minor

Summary. The manuscript aggregates robocall reports and call records from 65 countries, releases the first public multimodal international robocall dataset (8.7 million CDRs, 839 transcripts from 28 clusters, 677 recordings), describes 9-month collection methodology, and performs comparative analysis of calling patterns, co-targeting, campaigns, callback numbers, and linguistic features, concluding that robocalls are an international problem but with significantly higher severity in the US.

Significance. The public dataset release is a clear strength that can support reproducible follow-on work. If the severity comparison is shown to be robust after normalization, the findings would usefully inform US-centric and cross-border anti-robocall measures.

major comments (2)
  1. [Methodology and Comparative Analysis] Methodology and Comparative Analysis sections: the claim that severity is 'significantly higher in the US' is based on aggregated reports from 65 countries but supplies no description of normalization by population, telephone subscriptions, or reporting propensity; without these denominators the US excess cannot be distinguished from differences in data availability and incentives.
  2. [Results] Results section: no error bars, sampling methodology, or bias-correction steps are reported for the cross-country incidence metrics, leaving the statistical support for the headline severity claim unverifiable from the presented data.
minor comments (1)
  1. [Abstract] Abstract: the $1.1 billion loss figure is dated 'during 2025'; clarify whether this is a projection or a typographical reference to the collection window.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback on the comparative analysis. We agree that the severity claim requires explicit normalization and statistical details to be robust. We will revise the manuscript accordingly.

read point-by-point responses
  1. Referee: [Methodology and Comparative Analysis] Methodology and Comparative Analysis sections: the claim that severity is 'significantly higher in the US' is based on aggregated reports from 65 countries but supplies no description of normalization by population, telephone subscriptions, or reporting propensity; without these denominators the US excess cannot be distinguished from differences in data availability and incentives.

    Authors: We agree this is a substantive gap. The current manuscript presents aggregated counts without normalization. In revision we will add per-country incidence rates normalized by population and telephone subscriptions (sourced from ITU and World Bank data). We will also include a limitations subsection discussing reporting propensity differences and how our 9-month collection methodology (honeypots and report aggregation) attempts to address them where possible. revision: yes

  2. Referee: [Results] Results section: no error bars, sampling methodology, or bias-correction steps are reported for the cross-country incidence metrics, leaving the statistical support for the headline severity claim unverifiable from the presented data.

    Authors: We acknowledge the absence of these elements. The revision will add error bars to the incidence metrics, explicitly describe the sampling approach (including the 9-month collection window, data sources for the 8.7M CDRs, and how the 65-country reports were obtained), and outline bias-correction steps or their limitations based on the available data. revision: yes

Circularity Check

0 steps flagged

No circularity: purely observational data aggregation and comparison

full rationale

The paper performs empirical collection of robocall reports and call records across 65 countries, followed by descriptive analysis and cross-country comparison. No equations, fitted parameters, predictions derived from inputs, or self-citations are invoked as load-bearing steps in the central claim. The severity comparison rests directly on the collected dataset rather than any self-referential definition or reduction. This is a standard observational study whose validity hinges on data quality and normalization (addressed by the skeptic), not on circular derivation.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The paper is an empirical measurement study; no free parameters, invented entities, or non-standard axioms are described in the abstract.

axioms (1)
  • domain assumption Robocall reports can be aggregated across countries despite legal and privacy constraints
    The study relies on this premise to compile data from 65 countries.

pith-pipeline@v0.9.1-grok · 5876 in / 1228 out tokens · 56619 ms · 2026-07-01T04:26:32.040827+00:00 · methodology

0 comments
read the original abstract

Unsolicited automated phone calls (robocalls) are a serious threat: in the US alone, these calls resulted in reported losses of 1.1$ billion during 2025. Phishing and spoofing consistently rank among the most reported crimes within the FBI's Internet Crime Complaint Center, with phone call scams having the highest reported median loss. Combating robocalls is difficult due to many legal and practical constraints: robocalls often encompass multiple legal jurisdictions of different countries/states, the large volume of robocalls, their multilingual nature, the lack of publicly available data, privacy concerns with obtaining data, etc. We present a study of international robocalls, aggregating robocall reports from countries across all inhabited continents and contribute by providing new findings on international robocalls from 65 different countries. We also present the first publicly available multimodal and international robocall dataset: 8.7 million call detail records, 839 robocall transcripts from 28 identified robocall campaign clusters, and 677 robocall recordings. We describe our methodology for collecting robocall data over a 9-month period and provide a detailed analysis comparing robocalls in the US with those in other countries. Our analysis covers several aspects, including uncovering calling patterns, identifying co-targeting attacks, discovering common robocall campaigns, extracting callback numbers, analyzing linguistic differences among robocalls in the same language but different regions, and other insights. Our results indicate that although robocalls are an international problem, the severity of the threat is significantly higher in the US than in other countries. We provide steps for future research and suggest remedies to reduce the effectiveness of robocalls based on our analysis.

Figures

Figures reproduced from arXiv: 2606.31790 by Andro Mer\'cep, Ante Kapetanovi\'c, Emanuel Lacic, Kemal Altwlkany, Tomislav {\DJ}uri\v{c}i\'c.

Figure 1
Figure 1. Figure 1: The average number of monthly robocalls in the US over 2025 was 2.56 billion, which is the highest since 2019. to US consumers, with the volume of scam and telemarketing calls increasing by 15.6% in 2025 compared to 2024 [2]. 1.1. What exactly are robocalls? Definitions vary. According to the US Federal Communica￾tions Commission (FCC): “robocalls are calls made with an autodialer or that contain a prereco… view at source ↗
Figure 2
Figure 2. Figure 2: The Netherlands. NOS, part of the Dutch public broad￾casting system, released an article in which they state that the Dutch Fraud Help Desk received nearly 10,000 reports of scam calls that try to defraud people and extort money [58]. Scam￾mers are relying on AI-enabled technology to facilitate such calls. The news portal Telecoms reported that O2, the largest tele￾com in the United Kingdom, detected 150 m… view at source ↗
Figure 2
Figure 2. Figure 2: Info flyer published by the Croatian Police as part of Europol’s campaign relating to phone theft and fraud. If the callers present themselves as an organization the police in￾structs citizens to not call back numbers that the caller might have specified during the call. Citizens are instead advised to look up official phone numbers of those organizations. This info flyer was automatically translated using… view at source ↗
Figure 3
Figure 3. Figure 3: provides a simplified diagram of two different hon￾eypot configurations. We used the same honeypot consisting of the same phone numbers, but in two different configurations (setups/modes). The first setup is termed passive, which corresponds to Fig￾ure 3a. In this scenario, any incoming calls are simply re￾jected by the honeypot, and the honeypot does not interact with the calls. However, the honeypot regi… view at source ↗
Figure 4
Figure 4. Figure 4: Daily volume of phone calls registered by the honeypot. Days colored in blue represent calls registered while the honeypot was operating in passive mode, i.e. the honeypot does not interact with the calls, it simply rejects them. Days colored in orange indicate the interfering mode, i.e. the honeypot answers calls and plays warning messages to inform callers about the recording process. We noticed a patter… view at source ↗
Figure 5
Figure 5. Figure 5: Temporal distribution of robocalls by hour of day and day of week for US (left) and international (right) callees. Timestamps are in callee local time. Color intensity indicates the percentage of total calls in each region [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Distribution of calls per caller ID across the full dataset (US and international data combined) on log-log scale. The heavy-tailed pattern shows that most callers make few calls, while a small number of prolific callers generate substantial traffic. For US callees, robocall activity concentrates during busi￾ness hours. Calls to US numbers peak at 10:00 AM local time (9.7% of daily volume), with secondary … view at source ↗
Figure 7
Figure 7. Figure 7: Most frequent non-domestic caller country by destination country. The United States is the dominant external source for 16 destinations, followed by the United Kingdom for 5 destinations. dominant source for Denmark (3,553 of 13,253) and Sweden (47 of 126), and India is the top caller for Germany (72 of 73). Overall, the figure shows that international call traffic is not evenly distributed across countrie… view at source ↗
Figure 8
Figure 8. Figure 8: Word clouds of caller countries by US state, with word size proportional to the number of non-domestic calls. Nigeria is the dominant external source in 35 states, followed by Canada and Mexico, each leading in 4 states. 101 102 103 Co-targeting group size 10−4 10−3 10−2 10−1 100 CCDF US International [PITH_FULL_IMAGE:figures/full_fig_p011_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Complementary CDF of temporal co-targeting group sizes for US and international callees. Both distributions are heavy-tailed: a large majority of groups contain only a few caller IDs, while a small number of groups exceed 102 mem￾bers. Groups of size 1 are excluded. use a multilingual model, because the transcript set spans multi￾ple languages and we compare US and international calls in the same analysis.… view at source ↗
Figure 11
Figure 11. Figure 11: Duration of recorded US and international phone calls. The distributions for both regions follow a similar pat￾tern, with most calls being shorter than 20 seconds. 0 20 40 60 80 100 120 Vocal activity [%] 0 5000 10000 15000 20000 Number of calls US International [PITH_FULL_IMAGE:figures/full_fig_p012_11.png] view at source ↗
Figure 12
Figure 12. Figure 12: Percentage of vocal activity detected. In both re￾gions, a substantial amount of robocalls are silent, with very little vocal activity. This is a common phenomenon among robo￾calls and has been previously observed [4, 20]. “Blank” calls are usually made with the goal of determining whether the di￾aled number has voice capabilities (scouting calls). using voice activity detection features that trigger play… view at source ↗
Figure 13
Figure 13. Figure 13: Hallucinations caused by transformer-based automatic speech recognition can heavily impact the transcriptions. Hallu￾cinations are more prominent in recordings that contain a lower ratio of speech compared to silence. To the left, we show the most common words occurring in low speech ratio recordings, while the image on the right shows the most frequently occurring words in high speech ratio recordings. T… view at source ↗
Figure 14
Figure 14. Figure 14: Word clouds for English and Spanish, generated separately for US recordings and international recordings. Although robocalls were made in the same language, the word clouds differ, indicating that language is not the only predictor of robocall content - the region matters as well. 6.2.3. Regional Differences Between The Same Language We want to inspect whether there are differences between the most common… view at source ↗
Figure 15
Figure 15. Figure 15: Chord diagram showing the flow of languages towards callee countries. Country names are in ISO 3166-1-alpha-2 codes. 6.3.1. Campaign Discovery via Transcript Clustering Similar to [21], we apply Density-Based Spatial Clustering of Applications with Noise (DBSCAN) [100] to identify robocall campaigns based on their transcripts. Text normalization. Each transcript undergoes a text nor￾malization process in … view at source ↗
Figure 16
Figure 16. Figure 16: Robocall categorization per region (left - US, right - international). Similar to the results obtained with robocall cluster￾ization (Tables 4 and 5), scams related to financial services are more common in international robocalls, while tech scams are more common in US robocalls. Additionally, US robocalls contain a larger percentage of legitimate automated notifications. transcripts u and v is equal to t… view at source ↗

discussion (0)

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Reference graph

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