Typically that history is kept and it is kept for up to 20 years depending on which telco you look at. Those and the CDRs are gold for data mining and there are companies that specialize in doing just that.
It's insane if you think about it but the phone company knows as much or more about you than your mother or your spouse.
Or to the subscriber who last registered it to a network with a SIM, even though the SIM is not there now.
Typically that history is kept and it is kept for up to 20 years depending on which telco you look at. Those and the CDRs are gold for data mining and there are companies that specialize in doing just that.
It's insane if you think about it but the phone company knows as much or more about you than your mother or your spouse.