Carriers have far more customers than addresses. With carrier-grade NAT, a phone gets a private address inside the carrier's network, and many phones share one public address when they reach the internet.
For a website, this means one mobile address stands for a crowd. Blocking it would turn away every real customer behind it, so sites are reluctant to. That reluctance is the whole reason mobile proxies are accepted where other kinds are challenged.
You can see carrier-grade NAT from the outside: the address a phone shows on an IP-check page belongs to the carrier, and the same address turns up for other subscribers in the same area. Inside the carrier's network the phone holds a private address that the wider internet never sees.
Questions about CGNAT
Does CGNAT make mobile proxies anonymous?
It makes one address stand for many people, which is why sites hesitate to block it. It does not hide a browser's fingerprint or a signed-in account.
Is CGNAT only used by mobile carriers?
Mostly, but not only. Some home internet providers that are short of IPv4 addresses use it as well.
Related terms
- Mobile proxy
- A mobile proxy sends your traffic through an IP address of a phone carrier, on a real 4G or 5G connection. Sites are slowest to block these.
- IP reputation
- IP reputation is the trust a website places in an IP address, based on who owns it and how addresses like it have behaved before.
- IP ban
- An IP ban is when a website refuses requests from a particular IP address, usually after seeing too many requests or behaviour it disliked.
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