It is an intercom app (transceiver app).
You can have a conversation between iPhones connected to WiFi.
Features
・ One-to-many call
・ One-to-one call
・ Grouping registration
・ In-group calls (you can talk with the same passcode)
・ List of names of callable parties
・ Display of the other party's name
・ Bluetooth headset support
・ Automatic call can be started by detecting voice
・ Voice level adjustment
・ Supports call start sound
This app is a full-featured version of MyIntercomLite.