IMSI decoder for MCC and MNC
Split an IMSI into its MCC, MNC, and MSIN fields, with 2- or 3-digit MNC handling and a small built-in country lookup. Runs entirely in your browser — use dummy values only.
How to use this tool
What it does
Decodes an IMSI into its MCC, MNC and subscriber-identity fields.
When to use it
Use it to identify the home network of a subscriber identity from its mobile country and network codes.
Worked example
Paste an IMSI to resolve its MCC/MNC to a country and operator.
Input
Result
What this IMSI decoder does
The IMSI (International Mobile Subscriber Identity) is the number that ties a SIM or eSIM profile to a subscription on a mobile network. Defined in 3GPP TS 23.003, it is at most 15 digits and breaks into three fixed-position fields: the three-digit MCC (Mobile Country Code), the two- or three-digit MNC (Mobile Network Code), and the remaining MSIN (Mobile Subscriber Identification Number). This tool takes the digits you paste, strips spaces and dashes, validates them, and shows each field separately along with a country name when the MCC is in its small built-in map.
Together the MCC and MNC form the PLMN identity of the home network — the same pair you see in IMSI catchers, roaming agreements, and the home-network field of a 5G SUCI. The MSIN is the operator-assigned serial that distinguishes one subscriber from another within that network.
When to use it
Reach for this when you are eyeballing a SIM provisioning record, a test profile from an eSIM/eUICC lab, an HLR/HSS export, or a signalling trace and you just want to confirm which country and network a given IMSI belongs to. It is handy for sanity-checking that a freshly written test SIM carries the MCC/MNC you intended, or for explaining the structure of subscriber identities in documentation. It is not a subscriber database and not a live operator directory.
Input and output
Input is a string of digits — paste with or without separators; only 0–9 survive cleaning. The decoder rejects non-digits and anything longer than 15 digits, and warns when the value is shorter than a full 15-digit IMSI. Because MNC length is region-dependent and is not carried in the IMSI itself, you choose how to split: Auto guesses 3 digits for NANP-style ranges (MCC 310–316 and a few others) and 2 digits elsewhere, or you can force 2-digit or 3-digit. Output lists the MCC (with a country name when known), the MNC digits, and the MSIN. The operator row is intentionally left unresolved.
MCC
First 3 digits. Identifies the country/region. This tool maps a curated subset (for example 404/405 India, 310–316 USA, 234/235 UK, 262 Germany, 460 China) to a country name.
MNC
2 or 3 digits after the MCC. Identifies the operator within the country. Length varies by region; pick it with the selector when you know it.
MSIN
Everything after MCC + MNC. The operator-assigned subscriber serial. Shown verbatim; this tool does not interpret it.
Scope and honesty note
This decoder does not resolve the MNC to a named operator. There are thousands of MNC assignments and they change often, so a trustworthy lookup needs a maintained public MCC/MNC table rather than a hard-coded list that would quietly go stale. For operator resolution, consult a current public MCC/MNC reference such as the ITU/GSMA listings or community-maintained tables. The country map here is small and best-effort, not authoritative.
Common mistakes
- Confusing IMSI with ICCID. The ICCID is the SIM chip serial printed on the card; the IMSI is the subscription identity stored inside. Use the ICCID decoder for the former.
- Assuming a fixed MNC length. A 2-digit guess on a 3-digit MNC network shifts every later digit into the wrong field. Set the MNC length explicitly when you know the network.
- Expecting an operator name. This tool only maps the MCC to a country; it never names the carrier behind the MNC.
- Pasting a real IMSI. An IMSI is privacy-sensitive and can enable tracking. Work with dummy values; 5G even hides the IMSI inside the encrypted SUCI for this reason.
Related tools
More utilities
Parsers, decoders, and references for SIM, smart-card, and FIDO engineers.
Frequently asked questions
What are the parts of an IMSI?
An IMSI (International Mobile Subscriber Identity) is up to 15 digits. The first three digits are the MCC (Mobile Country Code), the next two or three are the MNC (Mobile Network Code) identifying the operator, and the remainder is the MSIN (Mobile Subscriber Identification Number) assigned by that operator. Together MCC plus MNC form the PLMN identifier of the home network.
How do I know if the MNC is two or three digits?
MNC length is region-dependent and is not encoded in the IMSI itself. North American (NANP) networks under MCC 310–316 typically use a three-digit MNC, while many other countries use two digits. This tool offers an auto heuristic plus explicit 2-digit and 3-digit options. When you know the operator, set the length manually for an exact split.
Does this tool identify the mobile operator from the MNC?
No. It includes only a small static MCC-to-country map and does not resolve MNC to a named operator. MNC-to-operator assignments change frequently and there are thousands of them, so a reliable lookup needs a maintained public MCC/MNC table. This tool deliberately keeps that out of scope and shows the raw MNC digits instead.
Is an IMSI sensitive, and does anything I paste leave my browser?
An IMSI uniquely identifies a SIM subscription and is privacy-sensitive — IMSI catchers exploit it for tracking, which is why 5G hides it behind the encrypted SUCI. Use only dummy values here. Either way, all decoding runs locally in JavaScript on this page; nothing you type is uploaded, logged, or sent to a server.
How does an IMSI differ from an ICCID?
The IMSI identifies the subscriber on the network and is held in the SIM's file system; the ICCID identifies the physical card itself. They are different lengths, different structures, and used at different layers.