Apart from this, the speed of the internet also slows down due to the SIM being dirty. Sometimes the network goes out suddenly due to the SIM being dirty. After this, if the network comes again, then you should always keep the SIM clean. If this is happening to you also then you should clean the SIM immediately. Because due to this the smartphone is not able to read the SIM. Due to this, the phone is not able to make calls.
These days the trend of WiFi Calling is also going on a lot. That is, calling can be done with the help of internet in WiFi area. But whenever we come out of the WiFi area, the calling is not possible. In such a situation, you should try that whenever you come out, after turning the phone on Airplane Mode once, turn off the Airplane Mode. By doing this the network of the phone is back again.