How Change my Galaxy J7(SM-J700F) IMEI ?!!

Im installed a custom rom (CM13 6.0) For My Galaxy J7 (SM-J700F) After that my IMEI had changed and i can't use my netword and calls again .
how i restore my old IMEI again ?!

from xda-developers http://ift.tt/1TNU5wE
via IFTTT