Usually, A monitor is necessary to get a serial number of the system so that you can use this information to add system on phone app.
But the phone can obtain the system's serial number by itself without a monitor. Below are the instructions.
1. Connect DVR to the router by an ethernet cable so that DVR accesses the Internet.
2. Search Sannce Vision in the Apple store or Google play store.
3. Make sure your phone is using wifi from the router and the router is connected to DVR by ethernet cable. In other words, DVR and phone are connected to the same router and in the same network area.
4. Run App Sannce Vision and click register user.
Create a user name and password by your email and use that account to cloud login.
5. Click plus icon at top right and click search to detect DVR's serial number.
6. It will detect system's serial number. Click OK to add system.
7. Tap device on the list and choose one camera to see live video.