Are they seriously trying to use an app on a cell phone to monitor cameras? We've got several systems in place and nobody gets serious about looking at what's going on without going to the DVR itself.
IC Realtime has been good. Dahua and HikVision, too.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw