It is a number we provide you. You do not have to use a SIM card for this. We allot this number using software, and then you receive the incoming messages of this website or app.
This is very likely to occur to a virtual number. It may be our fault, or the sender's. For example, this may arise if a website sends messages reluctantly, way too lengthy, or in a wrong manner (into the call system instead of the message system).
In this situation, you can terminate the transaction with this number, and the money will be adjusted to your balance. You can place an order for a new virtual phone number to receive the messages afterward.