Phone monitor app recommendations?

Marie
I've heard there are apps I can put on my phone to be used as a monitor with another phone. Any recommendations?
In more detail, I have an unused phone, and I want to use that phone as a monitor and have an app on my current phone (or my husband's current phone) that I can see through the monitor-phone. It will need to be able to be used with IOS and Android OS, please. I'd like one with night vision and two-way sound if possible. 
Thanks for any suggestions. 

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