clone samsung j700h clone network problem.need help

I have samsung j700h clone with strange behaviour.mt6572 flash type emmc
phone is receiving and sending msg.
Network signal ok.all 3g and 2g showing ok.
IMEI is ok no problem.

-Problem is when i make call,the phone cuts off the network and when call drop network is back.
-when i receive a call it cuts off network and restarts network again.

i have formated phone.
i have tried unlocking phone.
i have tried format nv with another nv from working phone.
almost everything i have tried.even change IMEI.

Someone can assist here?maybe hardware issue?