2) Check whether there are smudges or scratches on your SIM card's metal surface as a defective SIM card may affect signal stability. If necessary, contact your operator to obtain a replacement SIM.
3) Check whether “Blocked numbers” or “Filter spam calls” is active on your tablet: touch “Tablet” app-> touch settings icon
![](https://tct-open-document.s3.ap-northeast-1.amazonaws.com/image/Tablets/TCL+TAB+10S/image10.png)