How to judge whether Unicom Mobile's SMS package is outside the network?

In other words, if you use a mobile phone, all the mobile phone numbers belong to the same network, that is, within the network. Of course, Unicom and Telecom are the same. In fact, it doesn't make much difference whether it is a network or not. In the past, the charges for sending text messages were different, but now the charges for calling and sending text messages inside or outside the network are the same, so it is different.