I recently figured out, that the web site of my phone provider (mobile) mysteriously identifies me and automatically logs me into my account when I'm accessing with my android phone, as if it knew my phone number. (I used several browsers. When I'm using the phone as WLAN hotspot and access the same site from another device that doesn't happen.)

How does my phone provider do that? On the one hand, as a programmer, I'd like to be able to do that too, but on the other hand, as a user, I'm kind of scared. What information do they have, such that they (believe they) are able to identify me just by my device?

I hope this question isn't completely inappropriate for this site; feel free to add better tags — it's hard to find the right ones without knowing the Webmasters site at all.

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    They assigned your phone its IP address, so they already know whose phone it is. Looking that up is a trivial SQL query. Commented Apr 14, 2015 at 1:28

3 Answers 3


I'm working for a company that actually use it to make a "user detection". The phone number, and some other informations, are provided directly from the operators (telecom, orange, etc.), so there is no cookies or such things, there are simply a bunch of operators API to be called and they simply answer with the phone number, and some other informations. hope this helps.


My most obvious answer would be: you have an "auto login" cookie on your phone. This off course has nothing to do with your android phone.

  • What happens if you clear your browser data on your mobile phone and enter the site again?

  • What happens on a normal browser after you log on, close browser, open browser and go to the site again?

A second guess (altough I think that would be a lot harder but possibly do-able?) is that the provider site uses your phone location in conjunction with your current mcc, mnc, cellID and lac to "locate" you. This way it might know it could be you

(see: http://www.opencellid.org/)

  • Dear @Ronald, I can exclude the first case. That's the first thing I tried when I realised the phenomenon. In fact, I never logged in on the site using my phone, so even if it's a cookie, they must have 'identified' me with an obscure criterion the first time. I can log out manually on the site, but if I delete all cookies and return to the site, I'm logged in again. I haven't thought about identification by location, thank's for this idea. But it sounds unlikely, I'm doubtful with that.
    – Ben
    Commented Oct 25, 2013 at 6:39

It could access the special apps installed by the provider and get that information from it.(Just a guess!!, If your android has the provider customized OS with Apps of their own installed)

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