Wireless Joint

I don't believe this question is out of bounds, but if so, please let me know and I'll gladly withdraw.

I have a clear understanding of why some need to make some magic happen to modems when it comes to IMEI. I was recently told that some magic applied to the modem serial number is also a necessity in similar circumstances. Two questions I hope smarter folks than I can more fully answer (I'm just curious):

1. Why magic the serial number? Are all modem serial number formats so wholly unique from formats of phones, tablets, etc such that a carrier could flag a device as being mismatched to its plan based on the serial number?
2. What specific identifier are folks using in magic? ie, if someone were to magic a modem to have a Pixel 6 IMEI are they then also using the actual device serial for that Pixel 6 as well?

Again, hope my curiosity isn't out of bounds, not asking for any HOW, just a why and what. Thanks again for all the incredible wealth of knowledge and assistance that this board provides!

Some networks the imei and sim are married. You can't sim swap. I'm talking to you calyx and assurance wireless. Thats the biggest reason. To fool the network

It is thought that some carriers are retrieving and checking that the IMEI of a device also matches the serial number assigned to that device. The serial number on some of the modems may be updated must like the IMEI.

Carriers of branded devices have that info in their database, meaning if it is a Verizon device then Verizon has all the info from that device if it is a sprint device then likely Verizon does not have it.

There are rumors of carriers sharing some database info with competitor carriers in a sort of cooperation, as they do with blacklisted IMEIs, that each of them will do the same thing with it, they do have info from most all apple devices as it is not blocked in Albert (apple's main server is called Albert)but is blocked in Qualcomm and others so the sharing is needed if another carrier is to have the info across carrier platforms.

all that is needed is to 0 out the fid as it is what is sent back with every data packets returned info.
Maybe at some point it will be needed to actually write another fid from another device to it instead of zeros but zeroing it out has always worked up until now.