Dahua DMSS Remote Unlock Setup

I need my Dahua intercom pair (VTO door station and VTH indoor monitor) configured so that, when I am off-site, I can press a button in the Dahua DMSS app and release the door/gate lock. The call itself... (Budget: $10 - $30 USD, Jobs: Android, Asterisk PBX, Firmware, Network Administration, Security Systems, Software Architecture, Technical Support, VoIP)