[swiftcoder]

Unless you cycle across town every time you swap SIMs, I don't think this will help much. Just the fact that those two SIMs ping the same cell towers is enough for a bunch of data aggregators to correlate the numbers back to the same person.

[b112]

Plus, IMEIs are often sequential, and can be queried (like a mac address) in a DB. This helps prevent theft.

So they have one IMEI, they have all for that phone.