Does nextel track the phone or the sim chip
If you try to put the SIM from an older "two number" model phone ("iXX") into a newer "iXXX" model phone, then the iXXX will not have all of its features.
I also thought that you have to let Nextel know that you switched your SIM to a different phone, because their network system matches up the handset's internal ID (serial number) with the SIM ID, in order to have a valid combination that the network will recognize.
Anyone from the original Nextel CS team know the definitive answer? ...
If you break the phone - that is a different story. Service Centers verify SIM cards with the original MSN's to verify the correct model and may not service the phone if the original SIM is no longer in it.