What the existing connection tells
Phones limit background apps to save battery life. Additionally, residents can use different devices, silence modes, and notification preferences.
A notification that arrives at home but not at the outside is not a matter of course for an intercom: you want to know who is calling on the way.

Phones limit background apps to save battery life. Additionally, residents can use different devices, silence modes, and notification preferences.
Check the app permissions, notification categories, and any energy-saving settings on each device. Test not only on the same Wi-Fi as the base station, but also via mobile internet.
Set up notifications per user and only choose events that require attention. Make it clear to multiple residents who is receiving a call and what happens when no one responds.
Perform a test call with the screen locked, outside your own network, and in silent mode. Then check whether answering and opening are actually available.
Background rights, energy savings or account settings may block the notification.
No. Set up call groups to determine who should be available.