Are both IMEIs connected in phones with multiple SIMs?

If you are using it at home, then they can triangulate your location. Don’t know how long they save the logs from the cell towns, but probably years if they don’t save it forever. If they want to find you, they can keep using the historical data to find all the IMEIs you used at your home.

“If they want to find you, they can keep using the historical data to find all the IMEIs you used at your home.”

That all depends on how you use your phone. If you use airplane mode at home they cannot triangulate your location, and if you change your IMEI address every month they will only have access to historical data for maximum a month or less, depending on how much you change IMEI and IMSI.

I use my device at home with Wifi + airplane mode, they cannot triangulate my location with this. And when I go outside I take my 4G portable router with me, which I only activate when I’ve been gone from my home several KMs. And then i turn it on.

They can still get a general boundary of where you live. Sure, they don’t know your exact address, but they know you live in a certain area. It’s a good strategy – probably as good as it gets when it comes to privacy, but it does have some limitations.

Like I said, it all depends on how you want to use it. If you live in a city then leaving your house for a few KMs is just enough, if you live in a remote area… well that’s a different thing of course. But this is as best someone could get, if there is any other better way to go against IMEI tracking I’m all ears :).