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How to Turn a 4G USB Modem (Dcom) Into Your Own Rotating Mobile Proxy, Step by Step
What do you get, and when does it make sense?
A mobile proxy normally means renting addresses from a provider. With a Dcom you build it yourself: the IP address comes from the SIM card in your own modem, so there is no third party and no shared pool.
It makes sense when you need:
- a real mobile-carrier address for testing a site or app the way a phone on that network would see it;
- a stable mobile IP for an account you operate, which you can keep, or rotate only when you choose;
- many proxies on one PC, one per modem, each on its own port.
It is less attractive if you only need one datacenter address for a quick download. For that comparison see proxy types explained.
What you need
- A supported modem. The Dcom page in ADSSPEED has a list of supported models; common ones include the Huawei E3372h and E8372h and the ZTE MF79U.
- A SIM card with a data plan for each modem.
- A PC with ADSSPEED and a free USB port per modem. For several modems, use a powered USB hub.
- Decent signal where the modems sit.
Step by step
- Insert the SIM and plug the modem into the PC. Wait a moment for it to connect to the carrier.
- Open the Dcom › Proxy page in ADSSPEED.
- Click Scan. The app looks for connected modems only when you click, not in the background.
- Add or confirm each modem. Give it a name and a port. Choose whether the proxy needs a username and password.
- Set the automatic rotation in seconds if you want the IP to change on a timer, and apply it to the selected modem or to all of them.
- Click Start all servers. Each modem now serves its own proxy.
- Test with Check Live. It sends a real request through each proxy port, so you know the proxy actually reaches the internet.
Then copy the proxy in the format your tool needs. Each modem shows host:port or host:port:user:pass, in a local form for the same PC and a LAN form for other computers. Paste it into a browser profile's proxy settings, or into any tool that accepts a proxy. What is a browser profile?
Rotate the IP: three ways
- On a timer. Set the rotation interval in seconds, per modem or for all.
- On demand. Use the manual rotate button when you want a new address now.
- From your own tools. Each modem has a rotate link that you can copy and call, so a script or tool can ask for a new IP when it needs one.
Rotating means reconnecting the modem to the carrier. Many subscribers share carrier addresses (RFC 6888 describes carrier-grade NAT as sharing one IPv4 address among several subscribers), so the address you get next is the carrier's choice.
Keep logged-in sessions on a stable IP. For an account you operate, rotate only when you mean to, not in the middle of a session.
Optional limits per modem
When you add or edit a modem you can also set:
- a login (username and password) for the proxy;
- a cap on simultaneous connections;
- a bandwidth quota;
- an IP whitelist, so only chosen addresses can use the proxy.
Troubleshooting
| Problem | What to try |
|---|---|
| The modem isn't found | Check that the model is on the in-app list, the SIM is active, and the signal is good. Click Scan again; scanning only runs when you click. |
| The IP doesn't change after a rotation | The carrier may hand back the same address. Wait a moment and rotate again. If it keeps failing, use the manual reboot option, which restarts the modem and is meant for when rotating doesn't work. |
| Check Live fails | Make sure the SIM has data and signal, and the servers are started. Try rotating once, then test again. |
| Another computer can't connect | Use the LAN address, not the local one, and check that the PC's firewall allows the port and that your whitelist includes the other computer. |
| Slow connection | Signal is the usual cause. Move the modem, for example with a USB extension cable, to a spot with better signal. |
Use it responsibly
Use your own SIMs and modems for work you are authorised to do: QA, regional checks, and operating accounts you own or manage. Read your carrier's terms about sharing and reselling a connection, and follow the rules of the sites you visit.
Stop the servers when you are finished with them.
Frequently asked questions
Which modems work?
The app lists the supported models under its Dcom page, and the list covers many Huawei and ZTE USB modems, pocket Wi-Fi devices and routers. Popular examples include the Huawei E3372h and E8372h and the ZTE MF79U. Check the in-app list before you buy.
Does every modem need its own SIM card?
Yes. Each modem uses its own SIM and data plan, and each modem becomes one proxy with its own port.
Can other computers use the proxy?
Yes. The page shows a local address for the same PC and a separate LAN address for other computers on your network. You can also limit access to specific IP addresses with a whitelist.
Is the IP guaranteed to change when I rotate?
No. A new IP comes from reconnecting the modem to the carrier, and the carrier decides which address you get. It can occasionally hand back the same address, in which case rotate again after a moment.
Is it legal to make my own mobile proxy?
Using your own SIM and modem for your own work is lawful in most places, but your data plan may restrict sharing the connection, and reselling access can be restricted by your carrier's terms and by local law. Read your plan's terms. This is general information, not legal advice.
HTTP or SOCKS5?
Each modem's proxy accepts both, so use whichever your tool supports. For a browser profile either works.
Sources
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