SIM800l AT+COPS returns 0and AT+CREG returns 0,3

Hi all
Yeah I know there is similar questions in this community But they didn't help. It's for some days that I play with SIM800l.It's response to my at commands is good but when I want to send SMS I'll get problem.I think this Screenshot says most of story:

AT commands and it's response

u can see that I have signal (AT+CSQ = 19).but my module can't find and connect to operator (forgot to test AT+CREG but it returns 0,3) and I can set CREG to 1,3 by AT+CREG=1 command.Does it help?

oh at last I should say that I'm using lm2596 for supplying and my module blinks 70 times in a minute.more than 1 time in a sec (searching for network) and less than 2 time in a sec (connected)

ANY help would be appreciated :wink: