Usually, you need get a monitor to get serial number of system so that phone can use this infomation to add system by app.
But phone can get system's serial number by itself without a monitor. Below are steps.
1. connect DVR to router by ethernet cable so that DVR gets Internet.
2. search xmeye in apple store or google play store.
3. make sure your phone is using wifi from the same router and the router is connected to DVR by cable. In other words, DVR and phone are connected to same router and in same network area.
4. run app xmeye and click register user.
create a user name and password by your email and use that account to cloud log in
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 select one camera to see live video.