SIM destroyed, phone wiped. The IMEI still convicts.
The Supreme Court has settled that a mobile phone's permanent IMEI number survives SIM removal and can link a device to calls, towers, and locations in ways most lawyers overlook.
The Supreme Court has settled that a mobile phone's permanent IMEI number survives SIM removal and can link a device to calls, towers, and locations in ways most lawyers overlook.
When the SIM card is gone, the phone still talks
In a Delhi courtroom in 2025, a defence lawyer held up a mobile phone and argued: the SIM card was removed and destroyed. The device is a brick. There is no subscriber identity. There is no way to link this phone to any call, any tower, any location. The argument sounded clean. It failed. Because every mobile instrument carries a permanent digital fingerprint that no SIM card can erase — the International Mobile Equipment Identity number, or IMEI. And the Supreme Court of India has already settled what that number does, and why it matters when evidence hangs on it.
The Aadhaar of the handset
The IMEI is not a phone number. It is not a SIM card number. It is a unique identifier burned into the microchip of the device at the factory, assigned by the manufacturer, and it stays with that instrument for its entire life. Think of it as the Aadhaar of the mobile phone — permanent, non-transferable, and recorded every time the device makes or receives a call.
The Supreme Court laid this out plainly in Mohd Arif v State (NCT of Delhi). The Court observed that an active mobile phone has two components: "the mobile instrument and the SIM card." Every mobile instrument, the Court said, is assigned a unique identification number — the Instrument Manufactured Equipment Identity, or IMEI number. This number is not optional. It is not something the user can change. It is embedded in the hardware.
The Court then explained what happens inside the network. The mobile switching centre — the main server computer for the mobile service — "handles and records each and every movement of an active mobile phone." That record includes the "day and time of the call, duration of the call, calling and the called number, location of the subscriber during active call and the unique IMEI number of the instrument used by the subscriber during an active call."
This is the foundational function of the IMEI: it allows the network to identify the physical device, regardless of which SIM card is inside it. Remove the SIM, swap the SIM, destroy the SIM — the IMEI remains. And the network keeps logging it.
Three things the IMEI tells you that a SIM card cannot
- Track the device, not the subscriber. The SIM card identifies the subscriber — the person who bought the plan. The IMEI identifies the instrument itself. When a suspect swaps SIMs to avoid detection, the IMEI stays constant. The call detail records will show the same IMEI appearing across different phone numbers, at different times, in different locations. That pattern is evidence.
- Reveal the device's origin and age. The IMEI number is not random. It encodes the country of manufacture and the year of production. For forensic investigators, this can narrow down when and where a device entered the market, and sometimes even the specific batch. This matters when the defence argues the device could not have been at a certain location because it was not yet manufactured.
- Physically link the log to the handset. The IMEI is printed on the back of the handset, often below the battery. It can also be retrieved by dialling *#06#. This means the forensic examiner can physically confirm that the IMEI appearing in the call detail records matches the IMEI on the device recovered from the accused. That is a direct, verifiable link between electronic evidence and physical evidence.
What the network actually records
Many lawyers and corporate clients assume that call detail records only show the phone number and the tower location. That is incomplete. The mobile switching centre records the IMEI of the instrument used during every active call. This is not optional network behaviour — it is how GSM networks are designed to operate.
The Supreme Court in Mohd Arif confirmed this technical reality. The Court's observation that the MSC records "the unique IMEI number of the instrument used by the subscriber during an active call" is not a legal fiction. It is a statement of how cellular networks function. The IMEI is logged automatically, continuously, and without any action by the user.
This has a direct consequence for litigation. When a call detail record is produced in court, the IMEI column is not decorative. It is a piece of identification evidence that can be cross-referenced against the physical device. If the IMEI in the CDR matches the IMEI on the handset, the link is established. If it does not match, that is also evidence — it suggests the device used for the call was not the device recovered.
THE PLAY: When you receive a call detail record in discovery, check the IMEI column before you check the phone number column. The IMEI tells you which instrument was used. The phone number only tells you which SIM was inserted.
How this changes cross-examination
I have seen senior advocates spend an entire cross-examination trying to shake the tower location evidence. They ask about signal strength, about overlapping sectors, about weather interference. All of that is fair game. But they miss the IMEI.
Here is the move that changes the cross: ask the investigating officer whether the IMEI appearing in the CDR was matched against the physical device. If the answer is no, the chain of custody is broken. If the answer is yes, ask for the forensic report that confirms the match. If there is no forensic report, the match is hearsay.
The IMEI also defeats a common defence: "I lost the phone." If the accused claims the phone was stolen before the crime, the CDR will show the IMEI continuing to make calls after the alleged theft. That is direct evidence that the phone was still in use — and if the accused cannot explain who was using it, the inference shifts.
What lawyers don't tell their corporate clients about IMEI evidence
Corporate clients often think that if they change their SIM card, their phone activity becomes untraceable. That is wrong. The IMEI remains constant. If a corporate officer uses a company-issued phone for personal calls, then swaps the SIM to a personal number, the CDR will show the same IMEI appearing under two different phone numbers. That is how internal investigations catch employees who use company devices for side businesses.
Founders should know this: if you issue phones to your team, record the IMEI of each device at the time of issuance. That one step — a simple spreadsheet with the employee name, device model, and IMEI — can become critical evidence in a dispute over misuse of company resources, theft of confidential information, or even a non-compete violation.
CFOs should know this: when you sign a personal guarantee and the lender later claims you made certain calls from your phone, the IMEI in the CDR will confirm whether the calls were made from your device or from someone else's. If you use a separate phone for business, keep the IMEI record. It is your alibi.
The bottom line
The IMEI number is not a technical footnote. It is the permanent identity of the mobile instrument, recorded by the network every time the device is used. If you are litigating a case that involves mobile phone evidence — whether it is a criminal trial, a cheque bounce case, or a corporate dispute — the IMEI column in the CDR is where the real story lives. Read it. Match it. Cross-examine on it. And if you are advising a client, tell them this: the SIM card is temporary. The IMEI is forever.
