I want to add my phone to a security camera system already up 4 camera zosi system already running 

CameraFTP cloud service can provide cloud based storage for IP cameras and NVRs. Our service is compatible with almost all non-proprietary IP cameras and NVRs (meaning the device supports standard protocols such as FTP, SMTP, ONVIF and RTSP, etc. and is not locked in with the manufacturer's own service. ) 

It seems you want to use a phone as an IP camera? You just need to install CameraFTP Mobile Security Camera app for iOS or Android. It can turn an old smartphone/tablet as an IP Security camera or baby/pet monitor. It works even better than a regular IP camera or Pet/baby monitor as it supports two-way video and audio viewing or calling, and it is extremely easy. In this case, it does not require another NVR. The cloud service can act as a cloud-based NVR.

CameraFTP also supports all webcams. You can use a webcam as an IP security camera by installing our Webcam Security Camera app, or CameraFTP VSS software. The VSS software is very powerful. It can use an old PC as a CCTV NVR system. The software is free and the basic service is also free, you can save a lot of cost on NVR system. (The cloud recording service is not free). 

We have a lot of tutorial videos, please visit:

https://cameraftp.com/cameraftp/support/tutorialVideos.aspx