Build an Android PTT Press To Talk Walkie Talkie System

I'm looking for someone to build a walkie talkie app with a basic back end, a bit like Zello. What you will need to do: 1. Build a basic api using PHP and a SQL database. The different talk groups, users, the users status etc will all be stored in an SQL database and accessed via the API using get and post requests. 2. Create a server for streaming the audio too and from all the devices via a websocket. I'm not sure exactly how you want to do this, but it must be secure, and use the Opus voice codec. 3. Build an android app to turn the phone of device into a walkie talkie. It must use the API to login to the system and authenticate the users, get a list of the talk groups etc, then use the websocket to transmit and receive the audio. The system will also have a few features that need implementing, like GPS location tracking of the device and emergency button. I'm also open to suggestions. This is just a basic idea at the moment but hopefully with lots of future work.