Default What will happen if I install stock rom if I have Patched modem?

I have Omega ROM installed on my phone, and I got the message "Not registered on network" when I try to make call. IMEI is correct, I tried to install stock rom using odin, I still get this message, I install Omega v29 again and install patched nd3 modem, and every thing is fixed. Now I can make call and open mobile data and recieve SMS.

But I decied to buy LG G3, and I will give my Note 2 to my young brother, and of course I want to keep the stock rom and get OTA updates for him.

My Quesion, if I format my phone and install latest Stock rom using odin, should I flash the patched modem again? Or every thing will be good and no need to ( root and install custom recovery ) ?

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