The phone may lose the network due to the fact that you haven’t updated the SIM card, or you are in a area with bad connection, or maybe failed communication module. This was told to the Agency “Prime” the General Director of ANO "Digital platform" Arseny Weltzin.
There are three most popular reasons why a phone could lose connection, the first one you have is old and worn out SIM card. This physical storage medium is updated every two years, he added.
In addition, you may be in a area with bad connection — it can be not only a basement, but the building with wide walls, or you are far between repeaters. Any other time the appearance of radio anomalies also lead to the loss of communication.
