Door access question

So let me start out by saying im not sure this is doable but I would think it is. I live in an old condo building with an intercom based system for access control at the front door. What I would like to do is be able to buzz the door via an app on my phone. This only has to work locally as my phone still picks up my wifi network when I am outside. Im guessing I would need some sort of contact closure like the global cache ip2cc and then an app on my phone. Has anyone done anything like this? Will the ip2cc work? Or is there a cheaper way? I appreciate any help

Thanks in advance