iPhone 6s sim card issue

Hi Pro’s
I have an iPhone 6s stack on activation screen. When i check the IMEI, it shows up but the ICCID is unknown even with the sim card inserted. but sometimes it shows the ICCID for few seconds then disapears.
I finally got it activated but now, when i remove the sim card sometimes it still searching … or it will say no service"
any iea.