when I insert 2 sim cards it doesnt show network

in my country we use airtel and TNM, when i insert both sims in my redmi it doesnt show network it just say emergency calls,when i insert tnm only it reads but only on sim 2 and i cant make calls it just uses internet but no calls and sms when i insert on sim 1 nothing happens it just say emergency calls.......when i insert tnm on sim 2 and airtel on sim 1 they both dont read but when i vice versa they be oky but after some time they stop reading....whats the problem guys