How do I check if a phone's IMEI is blocked in India?

Send KYM followed by the 15-digit IMEI as an SMS to 14422, or use Know Your Mobile in the Sanchar Saathi app. Check both IMEIs on a dual-SIM phone. Blacklisted, duplicate or already in use means do not buy or repair it.

What does a blank Modem Firmware line mean on an iPhone?

The baseband is not starting. Solved cases traced it to the baseband power supply (capacitor, inductor or baseband PMU) or the baseband processor itself, after software and carrier causes were ruled out.

What should I check first when an iPhone shows No Service or SOS?

Apple's order: airplane mode on and off, restart, contact the carrier, update iOS and carrier settings, reinsert or replace the SIM, check dual-SIM lines and roaming. Only then treat it as hardware.

Is restore error -1 a baseband fault?

Apple does not list -1 among its hardware errors. Technicians commonly associate it with the baseband, so confirm with modem firmware, IMEI and measurements before any board work.

iPhone No Service Repair: KYM 14422 IMEI Block Check, Modem Firmware Blank, SOS

01

Step 0 (India, mandatory): check the IMEI block status before any repair

A phone blocked on CEIR as lost or stolen gets no service on any Indian network, and no board repair can fix that. Check every IMEI before you quote, open or buy the phone.

Read the IMEI in Settings › General › About or by dialling *#06#. Dual-SIM phones normally have two IMEIs (IMEI and IMEI2): check both. iPhone 14 and later have no IMEI engraving, so compare with the box or invoice.
Source: Apple Support - Find the serial number, EID or IMEI on your iPhone · Wikipedia - International Mobile Equipment Identity (dual-SIM phones normally have two IMEIs; *#06#)
Send the SMS KYM <15-digit IMEI> to 14422 (or use Know Your Mobile in the Sanchar Saathi app). One SMS per IMEI.
Source: DoT / Ministry of Communications (DG Telecom) - IMEI check: SMS KYM <15-digit IMEI> to 14422 · PIB - Sanchar Saathi app: telecom empowerment at citizens' fingertips (2 Dec 2025)
If the reply says blacklisted, duplicate or already in use: stop. DoT advises not to buy such a phone, and a blacklisted phone is blocked across all service provider networks.
Source: DoT / Ministry of Communications (DG Telecom) - IMEI check: SMS KYM <15-digit IMEI> to 14422 · C-DOT CEIR user manual for mobile users v03 (blocking and unblocking)
Only the person who blocked it can unblock it, on the CEIR portal with the 18-digit request ID from the block request (after recovery).
Source: C-DOT CEIR user manual for mobile users v03 (blocking and unblocking) · Sanchar Saathi CEIR - block / unblock lost or stolen mobile
Never change or “repair” an IMEI. Tampering with a telecommunication identifier is punishable with up to 3 years' imprisonment, a fine up to ₹50 lakh, or both, and DoT calls it cognizable and non-bailable. Anyone buying or selling used phones must check the national IMEI database first.
Source: Telecommunications Act 2023, Section 42(3)(c) - tampering with telecommunication identifiers · PIB / DoT press release 17 Nov 2025 - IMEI registration and consequences of tampering
Also check Settings › General › About › Carrier Lock: “No SIM restrictions” means unlocked. A carrier-locked iPhone can be unlocked only by that carrier.
Source: Apple Support - How to unlock your iPhone for use with a different carrier

KYM helper

IMEI (15 digits, from *#06# or Settings)

Open SMS to 14422

The IMEI stays on this device: it is only put into the SMS app on your phone, never sent to AIFlasher.

02

Baseband checker: symptom to next step

Pick the model and the symptom, answer the bench tests you have done. The result updates as you answer and lists its sources.

iPhone modelSymptom

03

What each cellular symptom points to

Status bar shows SOS, No Service or Searching — SOS means the phone is not on your carrier but can still make emergency calls through other networks. Apple's steps (airplane mode, restart, carrier, iOS and carrier settings, SIM) come before any board work.
Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad
“Invalid SIM”, “No SIM” or “SIM not supported” — Apple's order: active plan, carrier lock status, restart, carrier settings update, reinsert the SIM with the tray fully closed, test another SIM, then service.
Source: Apple Support - If you see 'Invalid SIM' or 'No SIM' on your iPhone or iPad · Apple Support - How to unlock your iPhone for use with a different carrier
Settings › General › About: Modem Firmware is blank, *#06# shows no IMEI — The baseband is not starting. In the solved iFixit cases the causes were the baseband power supply (capacitor, inductor or baseband PMU) or the baseband processor itself.
Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved) · iFixit Answers - iPhone 7 (Intel) IMEI but no service or modem firmware (solved)
Modem Firmware and IMEI present, but still no service — The modem boots, so first finish the carrier, SIM and software checks. The Repair Wiki iPhone 6 case traced this state to the baseband CPU (broken pads, reball); that finding is specific to the iPhone 6.
Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad · Repair Wiki - iPhone 6 No Service, Modem Firmware OK
Restore or update fails with error 1, -1 or another hardware error — Apple lists 1, 3, 11, 12, 13, 16, 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 56, 1002, 1004, 1011, 1012, 1014, 1667 and 1669 under “Check your hardware”. Error -1 is not on Apple's list.
Source: Apple Support - iOS update and restore errors
Panic log mentions baseband-pcie (link timeout to the modem) — Example: “apcie[3:baseband-pcie]::handleInterrupt: AF/Link timeout”. The responder pointed at the baseband or its power management; the case was never resolved. Decode the full log in the panic decoder.
Source: iFixit Answers - iPhone 11 Pro apcie baseband-pcie link timeout panic (unresolved)

04

Bench tests in order

Test	If yes	If no	Source
KYM (SMS to 14422) result is clean for every IMEI (not blacklisted, duplicate or already in use)?	—	Stop: do not repair or buy. A blacklisted phone is blocked on all Indian networks; only the owner can unblock it on CEIR.	Source: DoT / Ministry of Communications (DG Telecom) - IMEI check: SMS KYM <15-digit IMEI> to 14422 · C-DOT CEIR user manual for mobile users v03 (blocking and unblocking)
Settings › General › About › Carrier Lock shows “No SIM restrictions”?	—	Carrier-locked: only the carrier can unlock it. This is not a board fault.	Source: Apple Support - How to unlock your iPhone for use with a different carrier
Airplane mode on for 15 seconds then off, and a restart done?	—	Do this first: it is Apple's first step.	Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad
Carrier confirmed the account is active, there is coverage and the phone is not blocked?	—	Contact the carrier before opening the phone.	Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad
iOS and carrier settings are up to date?	—	Update iOS, then check for a carrier settings update on Wi-Fi.	Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad
SIM removed and reinserted, or a known-working SIM / eSIM line tried?	—	Reinsert the SIM; replace it if it is damaged.	Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad
Settings › General › About shows a Modem Firmware version?	The modem is booting.	Blank modem firmware: the baseband is not starting.	Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved)
Dialling *#06# shows the IMEI?	—	No IMEI together with blank modem firmware fits a baseband that is not powering up.	Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved) · Repair Wiki - iPhone 6 No Service, Modem Firmware OK
Do Wi-Fi and Bluetooth work?	In the iFixit iPhone 5 case Wi-Fi and Bluetooth worked while the modem firmware was blank.	Wi-Fi / Bluetooth also failing: check the connectivity page as well.	Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved)

05

Repair routes by branch

Apple: if the carrier confirms no account or network issue and a hardware issue is suspected, the phone may need service.

Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad

Modem firmware blank / no IMEI: power first, then the baseband processor

Finish Apple's software and carrier steps so a board repair is not started on a software fault.
Check the baseband power supply section first: capacitors, inductors and the baseband PMU, against the boardview of this exact board.
If the baseband supplies are correct, the baseband processor is next. In the iFixit iPhone 7 (Intel) case the baseband PMU was replaced without success and a baseband CPU reball fixed it.
Do not swap the baseband chip casually: replacing it requires reprogramming storage to pair the IMEI with the serial number.

Limits

Older boards such as the iPhone 6 have a baseband CPU without underfill; newer iPhones do, which raises rework risk.
These are single field cases (iPhone 5, iPhone 7 Intel). Confirm the sequence on your model's boardview.

Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved) · iFixit Answers - iPhone 7 (Intel) IMEI but no service or modem firmware (solved) · Repair Wiki - iPhone 6 No Service, Modem Firmware OK

Modem firmware and IMEI present, no service

Complete Apple's list: airplane mode, restart, carrier account and blocking check, iOS and carrier settings update, SIM reinsert or replacement, dual-SIM lines enabled, data roaming when abroad.
Only then treat it as hardware. Apple: if the carrier confirms no account or network issue and hardware is suspected, the phone may need service.
iPhone 6 only (Repair Wiki): the fault was the baseband CPU under the EMI shield with broken V1 / U1 pads; the fix was a reball with the pads jumpered. Do not apply this to other models.

Limits

No public source was found for a model-independent RF-path sequence (antenna, transceiver, front end). Use the boardview of the exact board.

Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad · Repair Wiki - iPhone 6 No Service, Modem Firmware OK

06

After the repair: verify before handing over

The KYM replies for every IMEI are saved in the dossier.
Signal bars on your carrier, a voice call both ways, an SMS and mobile data.
Settings › General › About shows Modem Firmware; *#06# shows the IMEI.
Restart and test again; test on a second SIM if the customer has one.
Save the case dossier below with the route used and the result.

Source: Apple Support - If you see SOS, No Service, or Searching on your iPhone or iPad

07

Board-level method (software and carrier ruled out)

Use this only after the Apple steps and a carrier check, with the modem firmware state recorded.

Inspect the baseband area and shields for liquid, corrosion, heat damage from earlier repairs and missing parts.
Diode mode on the baseband supply lines named in the boardview of this exact board; compare with a known-good board of the same model, never a generic number.
Powered: measure those supplies. A missing supply with its source present points to the parts between them; follow the enable in the schematic before replacing the baseband PMU.
On stacked (sandwich) boards, read the sandwich page before separating the layers.

AIFlasher does not publish baseband rail voltages, diode values or designators until they are sourced for the exact board. Record your own known-good readings in the dossier.

08

Common baseband repair claims, checked

✗ A no-service phone always needs board repair.

✓ In India, first check the IMEI with KYM (SMS to 14422). A CEIR-blocked phone gets no service on any network, and the only fix is an unblock by the owner.

Source: DoT / Ministry of Communications (DG Telecom) - IMEI check: SMS KYM <15-digit IMEI> to 14422 · C-DOT CEIR user manual for mobile users v03 (blocking and unblocking)

✗ A blocked IMEI can be repaired or rewritten.

✓ Changing an IMEI is tampering with a telecommunication identifier: up to 3 years' imprisonment and/or a fine up to ₹50 lakh, cognizable and non-bailable.

Source: Telecommunications Act 2023, Section 42(3)(c) - tampering with telecommunication identifiers · PIB / DoT press release 17 Nov 2025 - IMEI registration and consequences of tampering

✗ No Service always means an antenna or network problem.

✓ A blank Modem Firmware line with no IMEI means the baseband itself is not starting, which is a board fault, not the network.

Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved)

✗ Blank modem firmware means replace the baseband chip.

✓ Check the baseband power supply first. A new baseband chip also needs storage reprogrammed to pair the IMEI with the serial.

Source: iFixit Answers - iPhone 5 modem firmware blank and no IMEI (solved)

✗ Restore error -1 is an official Apple hardware code.

✓ Apple's hardware list does not include -1; the baseband link is a technician association, not an Apple statement.

Source: Apple Support - iOS update and restore errors

✗ All 2025 iPhones use the same modem.

✓ iPhone 16e uses Apple's C1, iPhone Air the C1X, and iPhone 17 / 17 Pro / Pro Max use Qualcomm modems. Board routes do not transfer between them.