Unhappy [Q] noise on display when dialling Z1 6903

Dear friends
i have a xperia z1 c6903 & update it with wifi for first time & update again with flash tools to latest kitkat for solve my problem.
but when i dialling a number i see a few noise on screen...i see noise when use 2g or 3g internet on phone.
any one have this problem on phone?

how can i solve it? at last time i flash general ROM with flash tools.