Telephone Expert’s Testimony on the Reliability of Ytel Records Admitted
Posted on September 24, 2025 by Expert Witness Profiler
Michael Anthony (“Plaintiff”) filed this putative class action against The Federal Savings Bank (“FSB”), National Bancorp Holdings, Inc. (“NBH”), and FDE Marketing Group, LLC (“FDE”) (collectively, “Defendants”), asserting violations of the Telephone Consumer Protection Act (“TCPA”).
The Plaintiff filed a motion to bar defense expert Jan Kostyun while Defendants filed a cross-motion to bar Plaintiff’s expert Aaron D. Woolfson.
Telecommunications Expert Witness
Jan Kostyun is an independent technology consultant with over 35 years of experience covering the areas of telecommunications, enterprise architecture, and information technologies.
He developed expertise in areas such as landline and wireless order entry, including the collection of subscriber contact information and initial implementation of the National Do Not Call registry and has extensive experience in database methodologies, data analysis, and data mining in addition to call center operations and various dialing systems, including those used for inbound and outbound calling campaigns. He has personally performed database queries and data analysis against hundreds of data stores [such as] National Do Not Call lists, Wireless Block identifiers, Number Portability transaction lists and telephone call records produced by both wireless carriers and businesses involved in dialing campaigns.
Telephone Expert Witness
Aaron David Woolfson has over 25 years of experience in developing and analyzing databases and telephone systems and establishing the interfaces between telephone systems and the networks that convey calls.
He has been qualified as an expert in other TCPA cases requiring him to analyze call records and compare them against records of leads.
Discussion by the Court
Aaron Woolfson’s Expert Report
Woolfson reached three conclusions after reviewing call detail records (“CDRs”) obtained from Ytel, FDE’s carrier: (1) that “there is a reliable method to identify which calls in the call records were made to telephone numbers (a) to which two or more times were called in a twelve month period by [FDE], and (b) that were registered with the [Registry] for more than thirty days before each of the calls”; (2) that “using the CDRs and Defendants’ call transfer logs, there is a reliable method to identify the calls in the CDRs that were to phone numbers that also appear in the call transfer log (“Live Transfers”); and (3) that he is “able to identify contact information, including names and mailing addresses, related to the individuals to whom the calls were placed, based upon the records that are maintained by phone carriers in their ordinary course of business.”
Defendants’ critique of Woolfson’s opinion essentially falls into two buckets—(1) disagreements about how he interpreted certain datapoints to reach his specific conclusions; and (2) concerns about the difficulties of his proposed process for identifying class members.
First, with respect to the underlying data relied upon by Woolfson, the parties agreed that the Ytel CDRs do not include call disposition information that affirmatively indicates if every telephone call placed by FDE actually connected to an active number on the Registry. Because of that, Woolfson determined that an appropriate measure of this critical detail was call duration.
Specifically, Woolfson sufficiently explained the process he used to query the data and then analyze the output. Basically, the Court found that Defendants attacked the reliability of Woolfson’s conclusions and whether they
are supported by the data, not the validity of the methodology he employed in forming his opinions.
Jan Kostyun’s Rebuttal Expert Report
Defendants offered the opinion of their rebuttal expert, Kostyun, in seeking to bar Woolfson’s testimony.
Plaintiff contended that Kostyun’s methodology is not reproducible, as evidenced by his deposition testimony that he ran “hundreds and hundreds of queries against the data” which he cannot itemize or reproduce.
Defendants explained that Kostyun’s analysis “was undertaken in a forensic manner” that involved both “simplistic” and “more complex” queries of the data, and the “entire database and structure” were produced to Plaintiff.
However, Plaintiff never contended that Kostyun used an unacceptable methodology for the relevant industry. The Daubert inquiry focuses on assessing if Kostyun’s methodology lacks analytically sound bases, not if his rebuttal opinions are correct.
Held
The Court denied both Plaintiff’s motion to bar defense expert Jan Kostyun and Defendants’ cross-motion to bar Plaintiff’s expert Aaron Woolfson.
Key Takeaway:
Both sides argued at length in their extensive briefs that the opposing expert has erroneously interpreted the relevant data, and as a result, the opinions reached are wrong. But such “arguments about how the selection of data inputs affect the merits of the conclusions produced by an accepted methodology” are substantive considerations rather than proper Daubert challenges.
Case Details:
| Case Caption: | Anthony V. The Federal Savings Bank Et Al |
| Docket Number: | 1:21cv2509 |
| Court Name: | United States District Court, Illinois Northern |
| Order Date: | September 23, 2025 |
