If your camera has the Real Time control setting, you can set it to On or Off. With Real Time On, the camera accepts and responds to requests from the user immediately. For example, you can use the "Take a Photo" to request that the camera take and send a photo immediately. When you request setting changes, your camera will take change settings immediately.
When you set Real Time to On, you will have to enter the camera's phone number into the app for real time control to work. This is the camera's phone number, not your cell phone number, because you are sending commands to the camera, not to your phone.
This feature is only available on some of the 3G models. It's not available on 4G/LTE models or that ATTx.
When Real Time mode is On, the camera can also send pictures somewhat faster than when it is off so the camera can take additional pictures with less time between them. However, when Real Time is On, the camera consumes more power because it's always connected to the cellular network so battery life is shorter.
Cameras that do not have Real Time have the Power Saving setting. When Power Saving is On (the recommended setting), the camera will uses less power so it has longer battery life but the time between photos will be a few seconds longer. If Power Saving is Off, the camera can transmit pictures in less time and take them closer together, but it will consume more power and the battery live will be shorter.
If you are going to use Real Time ON or Power Saving OFF, you probably will want to use an external power source.