How to find out if there is a number online?

Question

Telecom operators

The person just disappeared and this is not about him, there are no answers to SMS, I can’t call. How to find out if there is a subscriber in the network?

Answer 1

You need to send an SMS with delivery confirmation.
As soon as the subscriber appears in the network, a confirmation of delivery will come.
Just keep in mind that the operator does not store SMS for a very long time - SMS can be deleted in case of a long absence of a subscriber in the network (days).
Many operators provide access to third parties to information about the balance - by changing the balance and its general condition, you can understand how "alive" the number is.