You should see all XM texts (SMS and MMS) on your billings. These are the ones sent or received through XM servers.
You will not see any advanced messaging texts such as iMessage on iPhones and RCS on Androids on your billing, as these are sent and received through Apple or Google servers, whether they use WiFi or XM cellular data if not on WiFi. These will only show up on your device.
You will only see text messages using WhatsApp, Facebook, or other Apps within these Apps, not on your billing, as they do not use XM servers.