I assume in order to be able to decide to serve those 1Ghz frequencies, all the phones are going to ping the local towers regardless, so it doesn't matter.
Back on the tracking side of things...
AFAIKR 3G and above do not leak their IMEI/IMSI unencrypted. Of course nearly zero phones show or warn if encryption is used or not (though I think that's a setting in the SIM card).