Fix S2 cant recieve or make call

recently i get a samsung galaxy s2 that can't make any call out or recieve call
this is call hardware corrupt you cant fix this with flashing new firmware because i already flashing new firmware with all stock rom and custom rom but get the same result this is why i call hardware problem ,but we can fix this thing with some trick
i thing the main problem came from network problem so we try to fix this first with some trick
-mostly happend with korean model  like e12l or e120s or e120k
so let me tell you how to fix it
1 you can open dial pad and type *#9090# or 319712358 and type password in order to enter hidden menu
2 enter password 774632 or   996412 or  0821 
3 select network setting
4 select network mode ( if having this option or skip this)
5 than choose network type
6 you can change network type of samsung galaxy s2 to GSM 1900 or GSM all  or automatic depending on the network area of your phone accept it but this time i choose GSM 1900 for my s2