The app consumes 20 KB (KiloBytes) per hour when idle.
The audio encoder is chosen based on the connection type of both the sender and receiver.
If both are using WiFi, it will will use 45 kpbs. If either are using 2G, it'll switch to 12 kbps.
If using ZelloWork, the active data rate can be configured in the range between 8 kbps and 40 kbps.
Average monthly data usage is generally from 70-100 MB, although individual usage may vary.