Keeping the imei when going from R1L013 to R4C003 with a phone that has changed imei

I have a problem of keeping the imei that I have chosen when flashing from the patched SW R1L013 to R4C003. I tried to change the imei using SW R4C003 but it didn't work no matter how I tried. Then when I finally got it to work with R1L013 I tried to flash it with R4C003 in believe that it could work going from one SW to a newer one but the error message "Put in the right sim-card" showed up. How is the phone flashed so that I can keep R4C003, the changed imei and so that it doesn't want another sim-card? Need all the help I can get.

you need R4C003 patched flash file, normal flash file will not work