g800f strange problem!

1st of all i want to say that i have no orig backup, i receive this set in this condition and customer was in another service.

So, this set have problem only emergency call.

I try to reset efs but imei stil same:

Waiting ADB device… OK
Reading phone info…
Model: SM-G800F
Android version: 4.4.2
Product code:
Phone version: G800FXXU1AOG2
PDA version: G800FXXU1AOG2
CSC version: G800FITV1AOG1
CSC country code: ITALY
CSC sales code: ITV
HW version:
Phone S/N:
Modem board: SS222
RF cal date:
IMEI: 350695200123951
Checking Super user right… true
Backuping EFS… OK
Reseting EFS… OK
Rebooting phone… OK

Done with Samsung Tool PRO v.26.3

i try to write efs:

Waiting ADB device… OK
Reading phone info…
Model: SM-G800F
Android version: 4.4.2
Product code:
Phone version: G800FXXU1AOG2
PDA version: G800FXXU1AOG2
CSC version: G800FITV1AOG1
CSC country code: ITALY
CSC sales code: ITV
HW version:
Phone S/N:
Modem board: SS222
RF cal date:
IMEI: 350695200123951
Checking Super user right… true
Extracting EFS file… OK
Converting img to ext4… OK
Writing EFS to phone… OK
Rebooting phone… OK

i write cert and imei change, but when i reset again efs imei change again on orig imei again not .

This set have network prolem. i dont know if is a hw problem. Signal enter for a few moment, in that time is possible to make a call, exacly after call end signal go down, if i wait some time signal go on again, and go down after i end a new call.