I currently work for an spanish ISP, and I can tell you that this test will put a lot of stress in the ISPs network. Querying, for example, cellid for so many phones simultianeously is going to be a problem. Other data like IMSI and so on is not a problem because it's stored in a database.
For people who is scared of this, ditch your phones because extracting your location, subscriber id and other info is, honestly, trivial. It is not to do at scale, but if someone wanted to spy on you and had access to the ISP network, be it via hacking into it (very difficult in the one I work for, but may be possible), or using a law, they can know where are you with very little effort.
I currently work for an spanish ISP, and I can tell you that this test will put a lot of stress in the ISPs network. Querying, for example, cellid for so many phones simultianeously is going to be a problem. Other data like IMSI and so on is not a problem because it's stored in a database.
For people who is scared of this, ditch your phones because extracting your location, subscriber id and other info is, honestly, trivial. It is not to do at scale, but if someone wanted to spy on you and had access to the ISP network, be it via hacking into it (very difficult in the one I work for, but may be possible), or using a law, they can know where are you with very little effort.