Mobile proxy

Mobile carriers do not have enough public IPv4 addresses for their subscribers, so they place thousands of customers behind shared addresses using CGNAT. The consequence is counter-intuitive but important: on a mobile IP, sharing is the expected state. Any given address may carry the traffic of an entire neighbourhood.

What the sharing ratio actually is

A public address has 65,536 TCP ports. Carriers allocate them to subscribers in blocks — commonly 512 to 4,096 ports each — so one address serves roughly 16 to 128 subscribers concurrently, and far more across a day as blocks are released and reassigned. Detection vendors know this, and mobile ranges are flagged as such in the same usage-type databases that flag hosting ranges. The flag is not a penalty: it is the reason the address carries so little information about who is behind it.

Plausibility is not invisibility

A mobile IP does not make accounts unlinkable. It makes their co-location on one address unremarkable, which is a narrower claim. Thirty accounts sharing a carrier address is ordinary. Thirty accounts sharing a carrier address that were all created the same week, follow the same seed list and post within the same ninety seconds is still a cluster — the timing did the work, not the network. Mobile removes the IP as evidence; it does nothing about device isolation or behaviour.

How rotation works on a mobile proxy

A dedicated mobile proxy is usually a physical modem with a SIM in it. The provider exposes a rotation endpoint — an HTTP call to a URL — that tears down the data connection, the equivalent of toggling airplane mode. The carrier then assigns a new address from its pool, typically within 10 to 40 seconds. The new address stays in the same carrier ASN and usually the same regional block, and occasionally you are handed the address you just released. Carriers also reassign on their own schedule, which is rotation you did not ask for and cannot suppress.

The trade-offs

• Cost — the most expensive category, typically from $18.90 per dedicated IP, with cheaper dedicated-mobile products around $9.
• Latency — roughly 30 to 70 ms of baseline round trip on LTE and 15 to 40 ms on 5G, against 5 to 15 ms on a datacenter link, before tower congestion.
• Throughput — variable by time of day, since you are sharing a cell with real subscribers whose evening peak is also yours.
• Rotation — partly outside your control, which makes long uninterrupted sessions harder to guarantee than on a static ISP proxy.

Checking one before you rely on it

• Query an IP information endpoint through the proxy and confirm the org field names a mobile operator and the usage type reads as mobile, not hosting.
• Trigger the rotation endpoint and re-query. The new address should sit in the same carrier ASN — a rotation that lands you in a hosting range means the pool is mixed.
• Poll the exit address every minute for an hour without rotating. Unrequested changes tell you how stable a session can actually be.
• Measure round trip over the same hour. A flat sub-10 ms line is not a cellular connection.

The errors that cost accounts

The first is a device that contradicts its own network. A phone reporting no SIM, no carrier and a wifi-only connection state, whose traffic exits a mobile operator’s ASN, has two layers telling different stories. The second is your own concentration: strangers sharing the address are harmless, but pointing fifty of your devices at one modem rebuilds the cluster you paid to avoid. Reserve mobile IPs for the accounts you cannot afford to lose — at roughly ten times the cost of a residential gigabyte, putting an entire farm on mobile rarely pays for itself.