iPhone 18 vs iPhone 17 — IMEI & TAC Differences, and How to Tell Them Apart

Published: October 2026 · 5 min read

As iPhone 18 Pro and Pro Max units enter the secondary market, sellers misrepresenting an iPhone 17 Pro as an 18 Pro is one of the most common used-phone fraud scenarios. The easiest way to catch a mismatch — before you touch the device — is the TAC code: the first 8 digits of the IMEI that identify the exact model. This guide explains how iPhone 18 and 17 IMEIs differ and what to look for.

How TAC Codes Separate iPhone Models

Every iPhone model gets its own GSMA-assigned TAC (Type Allocation Code) — the first 8 digits of the IMEI. Apple requests new TAC allocations for each new iPhone model and configuration. The iPhone 17 Pro and iPhone 18 Pro are different device models, so they have different TAC codes, even though they look similar externally.

When you enter an IMEI into the checker on this site, it extracts the TAC and looks it up in a reference table. If a seller claims the phone is an iPhone 18 Pro but the TAC resolves to iPhone 17 Pro, that is a clear model mismatch. It doesn't prove fraud on its own — the seller could have made an honest mistake — but it warrants immediate clarification before any money changes hands.

iPhone 18 Pro vs iPhone 17 Pro — Key Differences

How to Tell an iPhone 18 Pro from a 17 Pro Physically

Apple made cosmetic design updates to the 18 Pro that can help confirm model identity when combined with the IMEI check:

• Colors: iPhone 18 Pro comes in Burgundy, Glacier, Silver, and Black. If the device is Desert, White, or Natural titanium — those are iPhone 17 Pro colors.
• Camera bump: The 18 Pro camera module is approximately 0.5mm taller than the 17 Pro. Most 17 Pro cases will not sit flush on an 18 Pro.
• Variable aperture: In the Camera app on the 18 Pro, manual Pro controls include an aperture slider showing ƒ/1.48, ƒ/1.8, ƒ/2.8, ƒ/4. The 17 Pro has no aperture control — it shows only the fixed aperture value.
• Settings → General → About: Model name is clearly listed as "iPhone 18 Pro" or "iPhone 17 Pro." A seller cannot change this without modifying the firmware.

Why the $100 Price Gap Matters for Fraud Risk

The iPhone 18 Pro starts at $1,199 — $100 more than the iPhone 17 Pro at launch. In the used market, this gap can be larger as 17 Pro prices drop while 18 Pro prices remain near retail. A fraudulent seller presenting a 17 Pro as an 18 Pro could net $150–300 extra depending on timing. The TAC check is a 30-second verification that eliminates this risk before you even meet in person.

IMEI Limitations: What the TAC Check Cannot Detect

The TAC code check confirms the device model. It cannot tell you about any of the following — which all require separate steps:

• Blacklist status — A correctly identified iPhone 18 Pro can still be reported stolen. Call your carrier. See our blacklist guide.
• Activation Lock — The most costly used-iPhone risk. Must be verified by powering on the device and going through setup. See our Activation Lock guide.
• Carrier lock — Model confirmation doesn't confirm unlock status. See our carrier lock guide.
• Internal hardware — A phone sold with a replaced main board may have a mismatched serial / IMEI. Apple's Settings → General → About will show "Unknown Part" for non-genuine replacement parts on recent iPhones.
• IMEI cloning — An iPhone 17 Pro with a cloned iPhone 18 Pro IMEI would pass the TAC check. This is rare but possible. Physical inspection (color, aperture control, camera bump) provides additional verification. See our IMEI cloning guide.