Closed mode is one of two Cell Booster Pro device modes of operation (the other being Open mode). With Closed mode, only FirstNet wireless users specified on the User List can use the Cell Booster Pro device.
Phone numbers not on the User List will still attempt to connect to the Cell Booster Pro, but will not be able to access voice, data, or texting. These devices may appear to have no service, or service without access to the network. When these devices leave the area, airplane mode might need to be toggled for them to access the AT&T and FirstNet network. To prevent this from happening, set the Cell Booster Pro to Open mode.