Who Pays the Bill of the GSM Line Used in the Offence? The Evidentiary Value of Bill Payments

Last updated: 17.10.2026 · Author: Attorney Coşkun Genç, Istanbul cybercrime lawyer

In identifying the actual user of a GSM line allegedly used in an offence, there is an investigative method that does not occur to most people but to which the Court of Cassation attaches great importance: examining by whom the line's bill payment history and, for prepaid lines, the credit top-up transactions were made. This method can be particularly decisive in "potato line" (patates hat) cases, where the subscription record does not reflect the real user.

How Are Bill Payments Examined?

In this context, establishing by whom, through which payment channel and from which account the bill amounts were paid, covering the period from six months before to six months after the date of the offence, can provide guidance. The fact that the payments were made by third persons other than the suspect may indicate that the actual use of the line may lie with different persons.

Where the payments were made by third persons, the real user of the line can be identified by taking the statements of those persons. For this reason, obtaining the payment records constitutes concrete and verifiable evidence as to the identity of the real perpetrator.

Which Record Should Be Requested Depending on the Payment Method?

The payment channel determines which record is to be requested; it is not sufficient that the bill appears as "paid" — the question to be asked is from which card or account, from which number or at which point the payment was made.

In a case in which the defendant claimed to have paid the bill amounts in cash at dealers, the 13th Criminal Chamber of the Court of Cassation required that the GSM company be asked in what manner and by whom the bills were paid, and reversed the judgment rendered without this inquiry having been made (E. 2019/10615, K. 2020/3085, 03.03.2020). A defence of payment at a dealer likewise carries weight when it is verified by the operator's records.

How Are Payment Records Requested from the Operator and the Bank?

Since the card, account and call details of the payer belong to third persons, these records are requested by a written request of the public prosecutor's office or the court. Article 147(1)(f) of the Code of Criminal Procedure (CCP, Law No. 5271) provides that the suspect shall be reminded that he or she may request the collection of concrete evidence, and Article 160(2) requires the public prosecutor to collect evidence in favour of the suspect as well; during the prosecution (trial) phase, a request for evidence may be rejected only in the limited cases set out in Article 206(2). The request is built in the following order:

1. Determine the period: At least six months before and after the date of the offence.
2. Ask the operator: Whether the line is postpaid or prepaid; the date, time, amount and channel of each payment; the paying card, account or calling number; the IVR voice recording.
3. Ask the bank: The holder of the card or account, the statement, and who gave the automatic payment instruction and through which channel; session and IP records.
4. Have the payers heard: Persons found to have made payments are asked who used the line and who provided the money.
5. Compare: The responses are assessed together with the subscription contract and the HTS records (historical traffic search – call detail records); where a response is incomplete, a further written request is sought.

Article 51(10) of Electronic Communications Law No. 5809 provides that the retention period of data shall be determined by regulation, being not less than one year and not more than two years from the date on which the communication took place; personal data that are the subject of an investigation, however, are retained until the relevant process is completed. If the request is delayed, data such as the calling number and the transaction record may no longer be obtainable. Article 60(19), added by Law No. 7571, obliges the operator to send the information and documents requested by the public prosecutor, the judge or the court within ten days; the public prosecutor imposes an administrative fine of TRY 50,000 to TRY 300,000 on an operator that fails to send them or sends them incompletely.

Which documents should be requested?

• ✓The subscription contract of the line and its annexes (copy of the identity document, signature, photograph)
• ✓The bill and payment statement covering six months before and after the date of the offence (date, time, amount, channel)
• ✓Card/account holder information from the bank and the statement for the relevant period
• ✓HTS records of the line used in the offence and of the line that made the payment (including base station data)

What Does the Court of Cassation's "Sibling Defence" Decision Say?

One of the most instructive decisions on this subject is the decision of the 8th Criminal Chamber of the Court of Cassation, E. 2019/20018, K. 2021/14817, dated 25.05.2021. In that case, the defendant argued that the GSM line registered in the defendant's own name was being used by the defendant's sibling. In the case, the bill of the line registered in the defendant's name had been paid with the credit card of the intervening party (katılan) through the IVR voice response system. The Court of Cassation stated that the truth of this claim had to be investigated and required that the sibling be heard as a witness after being reminded of Article 48 CCP, that it be determined by voice analysis whether the IVR voice recording belonged to the defendant or to the witness, and that the following inquiries be carried out (summary of the decision):

The hearing of the defendant's sibling as a witness after being reminded of Article 48 of the Code of Criminal Procedure; asking in detail which lines he or she used on which dates and in what manner he or she made the payments relating to the call charges; investigating by whom and by what method the bill payments for the relevant GSM line were made, covering the period six months before and after the date of the offence.

The decision reversed, on the ground of incomplete investigation, the judgment rendered without these inquiries having been carried out.

What does Article 48 CCP change in a sibling or family member defence?

Under Article 45(1) CCP, the spouse, the fiancé(e), ascendants and descendants, blood relatives up to and including the third degree, relatives by marriage up to and including the second degree, and persons linked by adoption may refuse to testify; a sibling is a second-degree blood relative. Article 48 CCP, in turn, provides that a witness may refuse to answer questions that may expose himself or herself or these relatives to prosecution, and that the witness shall be informed of this in advance. Since the sibling said to have used the line may incriminate himself or herself by answering, this reminder is mandatory.

Since the relative may refuse to answer, the defence should not rest on his or her statement alone; the payment records, voice analysis and HTS records should be requested together. In another case, the 8th Criminal Chamber of the Court of Cassation required that the person to whom the money for the payment was said to have been given be heard in accordance with Article 48 CCP and, where necessary, confronted with the defendant, and that the handwriting, signature and photograph in the subscription contract be examined (E. 2016/4311, K. 2017/439, 18.01.2017). Pointing to a relative may also lead to an investigation against that person.

What Is Voice Recording Analysis in IVR Payments?

In the same decision, the Court of Cassation also pointed to a type of evidence little known in practice: payments made through the interactive voice response (IVR) system. According to the decision, the voice recording of the payment transaction carried out by the IVR method must be obtained from the operator and a voice analysis must be commissioned. In this way, the identity of the person who paid the bill by telephone can be established through his or her voice, and the person who actually assumes the financial obligations of the line can be determined.

In short, while subscription records alone may be misleading, identifying the person who actually pays for the line can support abstract claims with material findings.

How Does the Investigation Expand for Payments Made Online?

For payments made over the internet, the scope of the investigation widens even further. In a case in which credit was purchased online without authorisation using the victim's credit card (misuse of bank or credit cards, Article 245 of the Turkish Penal Code (TPC, Law No. 5237)):

By its decision E. 2019/12225, K. 2019/14972, dated 12.12.2019, the 8th Criminal Chamber of the Court of Cassation held the following to constitute grounds of insufficient examination: the failure to hear the owners of the lines to which credit was loaded as witnesses; the failure to take the statement of the owner of the mobile telephone number registered when signing up to the website used in the offence; the failure to ask the relevant company by whom the e-mail address was created and in whose use it was on the date of the offence; and the failure to identify the subscribers who were using, on the date and at the time of the offence, the IP addresses from which the purchases were made.

When the payment investigation covers all digital payment channels, including bank, mobile payment and IP records, the likelihood of reaching the real perpetrator increases markedly.

Article 245(1) TPC punishes a person who obtains a benefit by using another person's card without that person's consent with imprisonment from three to six years and a judicial fine of up to five thousand days. Where a bill is paid with another person's card, the subscriber of the line directly becomes a suspect; who made the payment is therefore at the centre of the defence.

What Is Investigated for Prepaid Lines Where There Is No Bill?

Since there is no bill for prepaid (pay-as-you-go) lines, where and by whom the credit top-up transactions were made is investigated.

In its decision E. 2020/901, K. 2020/2969, dated 27.02.2020, the 15th Criminal Chamber of the Court of Cassation regarded as incomplete examination the failure to investigate whether the lines were postpaid or prepaid, whether there was any outstanding bill debt and, if so, by whom it was paid.

In the same decision, the Court of Cassation also required that it be determined by expert examination to whom the signatures and handwriting in the subscription contracts belonged, and that it also be discussed whether the act constituted the offences set out in Electronic Communications Law No. 5809.

In online credit top-up transactions, on the other hand, the actual user can be reached through the IP addresses from which the top-up was made and the telephone and e-mail details registered on the website.

How Is Bill Evidence Assessed Together with HTS Records and the Subscription Contract?

A bill payment alone does not prove who used the line; it becomes a strong basis when the payment record, the subscription contract and the HTS records point to the same person. With respect to a defendant who argued that the number which made the payment via IVR did not belong to him or her, the 8th Criminal Chamber of the Court of Cassation required that three pieces of evidence be collected together:

"…by obtaining from the relevant GSM company the voice recordings relating to the telephone numbers that called for the credit top-up and the bill payment, it should be determined whether the voice recording belongs to the defendant; by obtaining from the relevant GSM company the subscription contracts and any annexed documents relating to the telephone lines to which credit was loaded and for which bill payments were made or caused to be made, whether the signatures in the contracts belong to the defendant, … and further, by obtaining the detailed communication identification reports relating to the telephone lines whose bills were paid, covering the period before and after the date of the offence, it should be established beyond any doubt by whom the lines subject to the offence from which the calls were made were obtained and used…"

Court of Cassation, 8th Criminal Chamber, E. 2015/2931, K. 2015/23183, 21.10.2015

The assessment is carried out in six steps:

1. Subscription record: In whose name was the line opened; to whom do the signature and photograph belong?
2. Payment history: Who made the payments in the six months before and after the date of the offence, and through which channel?
3. Relationship between payer and subscriber: Does the paying card, account or number belong to the subscriber or to a relative?
4. Voice and digital trail: Voice analysis for IVR payments; IP, membership telephone number and e-mail for internet payments.
5. HTS and location: The base station where the line was located at the time of the offence, and calls made with the paying line.
6. Overall assessment: If the evidence does not point to the same person, the defendant benefits from the doubt (in dubio pro reo).

Common mistakes and exceptions

• Contradictory statements: In a case where the defendant first stated that he or she had paid in cash and later that someone else had paid, where it was established that the payment had been made via IVR from another line registered in the defendant's name and that the workplace in question did not exist, the Court of Cassation did not find the objection of incomplete examination well-founded (8th Criminal Chamber, E. 2022/1774, K. 2023/413, 09.02.2023). No definitive statement about the payment method should be given before the records have been seen.
• Failure to specify a date range: In the sibling defence case, the operator had been unable to send the IVR recording because no date range had been specified.
• Settling for the statement alone: If the payment channel and the paying account are not asked about, the statement does not show who financed the line.

Frequently Asked Questions

If I am not the one paying the line's bill, is this evidence in my favour?

Yes, it is an important defence argument. Establishing that the payments were made by third persons is a concrete piece of data indicating that the actual user of the line is a different person; however, it is assessed together with the other evidence.

Does the court investigate bill payments of its own motion?

It is required to do so; however, in practice this may be overlooked. It is important that the defence makes an express request to this effect and objects to incomplete examination.

Is it an offence to make regular payments for someone else's line?

It is not an offence in itself; however, it may give rise to an investigation into whether the person making the payments for a line used in an offence is the actual user of the line or a person who participated in the offence.

GSM Line and Bill Payment Evidence with an Istanbul Cybercrime Lawyer

In cases where a line registered in one's name has been used in an offence, the outcome is determined by three points: requesting the payment records before the retention period expires and with the correct date range, having the record appropriate to the payment method entered in the file, and interpreting these records together with the subscription contract and the HTS records. Av. Coşkun Genç Law Office provides legal assistance in cybercrime investigations and prosecutions conducted in Istanbul at the stages of preparation before the statement, drafting of evidentiary requests and the hearing of witnesses. As an Istanbul cybercrime lawyer, our aim is to prevent the subscription record alone from turning into an accusation.

Those wishing to obtain the assistance of an Istanbul cyber crime lawyer may request a preliminary assessment through our contact page, together with the summons to give a statement or the indictment, the bill statement and any response letters from the operator or the bank. For our field of practice, you may refer to our cybercrimes page.

Sources

1. Electronic Communications Law No. 5809, Articles 51, 60 – mevzuat.gov.tr · Art. 51 · Art. 60
2. Law No. 7571, Official Gazette 25.12.2025, No. 33118
3. Code of Criminal Procedure (CCP, Law No. 5271), Articles 45, 48, 147, 160, 206 – mevzuat.gov.tr · Art. 48 · Art. 147
4. Turkish Penal Code (TPC, Law No. 5237), Article 245 – mevzuat.gov.tr · Art. 245
5. Court of Cassation, 8th Criminal Chamber, E. 2019/20018, K. 2021/14817, 25.05.2021
6. Court of Cassation, 8th Criminal Chamber, E. 2019/12225, K. 2019/14972, 12.12.2019
7. Court of Cassation, 15th Criminal Chamber, E. 2020/901, K. 2020/2969, 27.02.2020
8. Court of Cassation, 8th Criminal Chamber, E. 2015/2931, K. 2015/23183, 21.10.2015
9. Court of Cassation, 8th Criminal Chamber, E. 2016/4311, K. 2017/439, 18.01.2017
10. Court of Cassation, 8th Criminal Chamber, E. 2022/1774, K. 2023/413, 09.02.2023
11. Court of Cassation, 13th Criminal Chamber, E. 2019/10615, K. 2020/3085, 03.03.2020