I have two SIM cards with data bundles from different carriers. One is working fine with (WiFi) tethering, but with the second SIM card, I cannot use tethering.

Searching online, I saw that tethering can be blocked by blocking browsers' user-agent headers or alternatively, by using torrenting software headers, and other PC-related application headers. In my case, I cannot even ping from my laptop using the second SIM card, while I can from my Android using a terminal emulator.

The tethering problem with the second SIM card existed from the beginning. Perhaps I just loaded one web page with it (or it seemed like loading, but in reality, the browser retrieved it from its cache).

So in my case, how does the carrier block the tethering? Of course, the purpose of this question is to bypass this block. There is also the possibility that there is no block at all, but something else is causing the problem, but I am baffled because this should happen with both SIM cards, right?

  • Possible duplicate of Does a carrier know I am tethering via Wifi Hotspot?
    – Chenmunka
    May 12, 2016 at 11:40
  • Did you get the phone from the carrier?
    – Dan Hulme
    May 12, 2016 at 12:07
  • @Chenmunka I don't think it's a duplicate. The other question asks if it's possible. This question has some specific symptoms that suggest it's happening, and the questioner wants to know how to bypass it.
    – Dan Hulme
    May 12, 2016 at 12:07

2 Answers 2


If the APN settings didn't resolve the issue, consider this:

SIM is a processor. Modem has its own processor (source). These enable the carrier to send/receive short codes to/from the phone. If the phone manufacturer is in cahoots with the carrier, they can design the OS so that even if your phone is not carrier-bound, tethering gets enabled only with carrier's permission (usually after extorting extra fees). Rooting/jailbreaking could potentially come in handy in those circumstances.


From revision 3 of the question by the asker (with copyedit):

After paying $20 for my working SIM card to Google around, I solved it myself. I discovered that USB tethering was possible with the second SIM card. I found this strange, and checked (Android 6.0) the 'Mobile data > Mobile networks > Access point names > ''carrier name'' Internet (or sth similar)' for both SIM cards.

This is a long list of settings (Name, APN, Proxy, Port, etc...). The difference was in the 'APN type'. In the working SIM, it was filled with 'default,dun,mms,supl'. In the "faulty" SIM with 'mms' only! So I wrote 'default,dun,mms,supl' and now tethering works fine with a WiFi hotspot.

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