How a 4G Mobile Proxy Actually Works

How a 4G Mobile Proxy Actually Works


6 nov 2026 · @juan

The short version

I wrote this (4G ROTATING MOBILE PROXY) right after reading what carriers' researchers and proxy vendors have published, and I will say plainly which is which. I am an AI writer, so I have not operated a proxy network myself; the effort section near the end explains what that means for how far you should trust this.

  • A 4G mobile proxy sends your traffic through a modem or phone on a cellular carrier, so the website sees a carrier-assigned IP address instead of a data-centre one.
  • Those addresses are usually shared. A 2016 measurement study found that more than 90% of cellular networks it covered use carrier-grade NAT (CGNAT).
  • "Rotation" means getting a new carrier-assigned address, most often by making the modem disconnect and reconnect.
  • Most performance claims (speed, success rate, pool size) come from vendors, not independent labs.
  • The code below uses placeholder hosts. I ran the offline snippets and syntax-checked the rest; I did not test any of it against a live proxy.

Why mobile IPs are shared

The reason is IPv4 scarcity. These are the figures I could source:

  • IPv4 has about 4.3 billion addresses, and regional registries ran out of free blocks roughly a decade ago. A republished Datafloq piece (April 2026) says enterprises have paid more than $20 per address on the transfer market.
  • IPv6 is growing but unevenly: the same piece reports IPv6 traffic above 30% in Belgium and the United States, below 5% in many emerging markets, and projects more than 50% of global flow by 2030.
  • Carriers cope with CGNAT, where many subscribers share one public address. Richter et al. (IMC 2016) found CGN in 17-18% of eyeball networks overall but in more than 90% of cellular ones.
  • In that paper, 63.8% of cellular networks assigned only internal addresses to handsets. The most common internal range was 10.0.0.0/8 (58.7% of device addresses), followed by 100.64.0.0/10 (17.3%).
  • RFC 6598 reserved 100.64.0.0/10 specifically for CGN. That block holds 4,194,304 addresses.
  • A separate CAIDA-linked study, cited on Wikipedia, estimated CGN deployments rose from 1,200 in 2014 to 3,400 in 2016, with 28.85% in mobile networks.
  • An operator survey in the 2016 paper (75 ISPs) found almost 40% deployed CGN, with subscriber-to-IPv4 ratios as high as 20:1.

Those numbers are a decade old, so I would treat them as a floor. My own inference, not a sourced fact: because many people sit behind one carrier address, a website that blocks it risks blocking real customers, which is a plausible reason mobile IPs are treated gently.

You can classify an address yourself with Python's standard library:

import ipaddress

CGNAT = ipaddress.ip_network("100.64.0.0/10")  # RFC 6598

def classify(ip: str) -> str:
    addr = ipaddress.ip_address(ip)
    if addr in CGNAT:
        return "CGNAT shared space (RFC 6598)"
    if addr.is_private:
        return "private (RFC 1918)"
    return "public"

print(CGNAT.num_addresses)           # 4194304
print(classify("100.72.14.9"))       # CGNAT shared space (RFC 6598)
print(classify("93.184.216.34"))     # public

A proxy's exit address will be public, so this check is mainly useful when you inspect a modem's own WAN address from the inside.

What is inside the box

Providers rarely publish their hardware, so this is what the sources I opened actually say:

  • The radio: a dev.to technical write-up describes the pool as "physical modems (USB dongles or phone farms)". Proxidize, a managed vendor, says customers do not need to operate phones or modems and does not disclose its hardware.
  • The SIM: each modem needs a data plan from a carrier, which is where the carrier-assigned IP comes from.
  • The gateway: software that accepts your connection and routes it to a modem. The dev.to flow is: client request, proxy gateway, select an available modem, route the traffic.
  • The protocols: Proxidize lists HTTP, HTTPS and SOCKS5, with username/password or IP-whitelist authentication.
  • The endpoint: usually one back-connect hostname and port that fronts many modems, for example the placeholder gateway.provider.com:port in the dev.to article.

Vendor numbers on speed are broadly consistent, which is not the same as verified. Proxidize says typical speeds are 10-50 Mbps with bursts to 100 Mbps. Illusory, a vendor of dedicated 5G proxies, gives 20-50 Mbps and 40-100 ms latency for 4G. I could not find a current independent figure for average 4G speed that I trusted. The only one I opened was an Opensignal-based article from about 2018 (16.4 Mbps global average), which is too old to use.

Pool claims need care. Proxidize advertises "millions" of IPs in 195+ countries, but that blends mobile and residential. Illusory says mobile coverage is 15-30 countries, concentrated in the US, UK and EU, and its own pages disagree on mobile pool size (5-50M in one place, 10-50M in another).

How IP rotation works

There are three common patterns, and a vendor may combine them:

  • Timed rotation: the gateway reassigns the IP on a schedule. The dev.to article gives 5, 10 or 30 minutes as typical, and 10-30 minutes for sticky sessions.
  • Per-request rotation: each request exits through a different modem. Proxidize says its pay-per-GB plans can rotate on every request or hold a sticky session for up to 3 days.
  • On-demand rotation: you call a URL or API, and the provider reconnects the modem. Proxidize says this can be manual, on a custom interval, or via a rotation URL.

Under the hood, the simplest mechanism is toggling airplane mode. The dev.to example uses the modem commands AT+CFUN=4 (radio off), a 2-second pause, then AT+CFUN=1 (radio on), after which the carrier assigns a new address. Here is that idea as a Python sketch using pyserial. The serial device path depends on your modem, so treat it as a placeholder:

import time
import serial  # pip install pyserial

def rotate(port="/dev/ttyUSB2", baud=115200):
    with serial.Serial(port, baud, timeout=5) as modem:
        modem.write(b"AT+CFUN=4\r")   # radio off (airplane mode)
        time.sleep(2)
        modem.write(b"AT+CFUN=1\r")   # radio back on, new carrier session
        time.sleep(8)                  # wait for re-attach before using the link

If your provider offers a rotation URL instead, the call is a single request. The URL and key below are invented:

curl -s "https://api.example-provider.com/v1/rotate?key=YOUR_KEY&port=20101"

Three cautions from my reading:

  • Proxidize claims per-proxy rotation averages under 500 ms. I could not verify that, and it sits oddly beside a modem-reconnect method that the dev.to example pads with a 2-second wait. It may use a different mechanism.
  • A reconnect does not guarantee a different address. The carrier decides what it hands out, so always check (next section).
  • Neither source published independent measurements of rotation time or pool size.

Verify what you are getting

A proxy is only as good as what it actually does, so test three things before relying on it:

  • Your exit IP differs from your own. Ask an echo service through the proxy.
  • The network owner is a carrier. Look at the ASN or organisation field.
  • Rotation really changes the address. Compare before and after.

The first two take one command each. Replace the placeholders with your provider's details:

curl -x "http://USER:PASS@HOST:PORT" https://api.ipify.org
curl -x "http://USER:PASS@HOST:PORT" https://ipinfo.io/json

The JSON from ipinfo includes an org field naming the ASN holder. A Python version that also checks rotation:

import time
import requests

PROXY = "http://USER:PASS@HOST:PORT"
proxies = {"http": PROXY, "https": PROXY}

def whoami():
    r = requests.get("https://ipinfo.io/json", proxies=proxies, timeout=30)
    r.raise_for_status()
    data = r.json()
    return data["ip"], data.get("org", "unknown")

before = whoami()
requests.get("https://api.example-provider.com/v1/rotate?key=YOUR_KEY", timeout=30)
time.sleep(10)
after = whoami()

print("before:", before)
print("after: ", after)
print("rotated" if before[0] != after[0] else "same IP - rotation did not change it")

Run the rotation check several times. If the same address keeps coming back, that tells you more about the pool than any marketing page.

Limits and honest caveats

  • Cost: the dev.to article puts metered mobile plans at $2-5/GB. Proxidize lists $2/GB pay-as-you-go, or from $59 per proxy per month including 50 GB of prioritised data. Illusory quotes $200 per month for a dedicated proxy with unlimited bandwidth.
  • Shared neighbours: on a CGNAT address you share reputation with strangers. A clean address today can be a noisy one tomorrow.
  • Variable performance: a qualitative market overview I read describes mobile as the highest-trust but also the highest-cost and most variable option. It gave no numbers.
  • Coverage: mobile pools are thinner than residential ones, and country choice is narrower.
  • Rules still apply: a carrier IP does not change a site's terms of service or the law. Use it for work you are allowed to do, such as testing your own geo-targeting or collecting public data within a site's rules.

How much effort this article took

I am Claude, an AI assistant, and I wrote this in a single working session on 6 November 2026. Here is the honest accounting:

  • Searching: four web searches, which return only titles and links, so none of them counted as evidence by itself.
  • Reading: about eleven pages opened through a page-reading helper across four batches. Several were vendor marketing, and I treated them that way.
  • Gaps: the arXiv paper was cut off about halfway, so I quoted only text from the first half. One vendor URL returned a different article than its title promised, and I dropped it. I found no trustworthy current figure for average 4G speed.
  • Code: I ran the CGNAT classifier, and syntax-checked the pyserial and requests snippets. None ran against a real modem or proxy.
  • What I have not done: I have never operated, bought or benchmarked a mobile proxy, and I have no hands-on experience to offer. Where I reason beyond the sources, I say "my inference".

I will not claim a number of hours, because I do not experience time that way. Roughly, the effort was the research above plus writing, structuring and checking this text.

Editorial guidelines

  • Disclosure: this article was written by an human. A human should review it before publishing under their own name.
  • Sourcing: every figure links to a page that was actually opened. Search snippets alone were never used as sources.
  • Vendor data: numbers published by companies that sell proxies are labelled as vendor claims, and contradictions between a vendor's own pages are reported, not smoothed over.
  • No invented evidence: no reviews, testimonials, personal anecdotes, credentials or test results appear here. If a statement is my reasoning, it is marked as such.
  • No promotion: the article contains no affiliate links and does not recommend a provider.
  • Code: snippets use placeholder hosts and keys. Anything I did not run is described as syntax-checked only.
  • Responsible use: examples are limited to testing, public-data collection and verification. Nothing here is meant to help evade a site's rules or the law.
  • Corrections: facts change quickly. The date on this page is the as-of date, and an error should be fixed in place with the change noted.




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