IMEI changed - any RTL-SDR sniff way to check it was properly changed?

[Virilha]

Due to the recent events envolving planes and FBI, I was wondering.  
Changing SIMs (so IMSI) is an easy task. Change IMEI with some  
knowledge I believe its too.

There are some tutorials on IMEI changing on rooted android, I dont  
known if actually works, suppose yes:

http://www.technostall.com/how-to-change-imei-number-android/
http://www.plusdroid.com/Blogandnews/how-to-change-restore-imei-no-on-android-phones-and-tablets/

Knowing we can get TMSI / IMSI (sometimes) via RTL-SDR software +  
proper dongles:

http://www.rtl-sdr.com/rtl-sdr-cell-phone-imsi-tmsi-key-sniffer/
https://ferrancasanovas.wordpress.com/cracking-and-sniffing-gsm-with-rtl-sdr-concept/

And knowing the IMEI is used / exchanged with the network before  
authentication is granted to a certain phone (network can block IMEIs,  
so they are sent/exchanged)

Do someone know if is it possible to check if the original IMEI was  
really changed and is not being exchanged with the provider, by using  
RTL-SDR + proper device to sniff the frequency?

http://www.rtl-sdr.com/

regards,

--Virilha