alarm system sim card upgrade to 3G or 4G
following all over the world's telecommunications ugprade, 2g will be gone, 3g and 4g is common, 5g will come, too. in the past, all the gsm alarm system use 2g sim card,
so all the gsm host should upgrade to 3G at least. 850/950/1800/2100MHz. our gsm alarm system had upgraded to 3g/4g, can support any kinds of sim card to work.
welcome customer to visit our factory and order.