It is impossible to get through to the phone, is there a problem in the hardware, software or sim card?

Question

Do it yourself

As it turned out, a problem arose yesterday, when the phone was turned on, everyone received a message that I was not online, the problem disappeared immediately after I called another subscriber, but I'm worried that this could happen again and I wonder what the problem is in hardware, software or sim card. Maybe someone had something similar and knows what the problem is, otherwise, due to the absence of a problem, now I can’t even determine what exactly it was.

Answer 1

If during the period of unavailability of the phone you did not look at the screen, you should go to a fortune teller. If you saw a message like "No sim" or "sim error", then the problem is in the SIM card or in the phone. If "no service" or "no signal" - in the phone or in the base station.
If the phone does not write internal logs, and the problem does not recur, you cannot do without a fortune teller.
If availability for an incoming call is critical - get a dialer phone and turn on forwarding to a spare number on the main number when unavailable.

Answer 2

Psychics on vacation, answers to your question - a guessing game.

Answer 3

It was - "cool" iPhones and Samsungs were not available - voice boxes turned on, "simple" Nokias received calls. Outgoing communication worked on all devices, connection and antennas on all devices were OK.
The problem was in the telecom operator, and eventually went away.