Trying out phone calls, i was able to set the phone into a state where a phone connection still existed, but was not visible nor controllable anymore. Steps to reproduce:
- Log in to phone
- Establish a call.
- Press the up-arrow to manage the phone application.
- Close the phone application swiping it up.
At that point, the connection still exists, but it is not longer visible or controllable anymore. Most particular, it cannot be terminated. If one opens the phone app again, it does not show the ongoing connection but offers only a new call and not to hang up. Thus no visible indication is given, that one is still connected, here, or elsewhere.
The very first time this happened, i actually expected, that the connection was closed, when i closed the app and was surprised, that the line was still active, but that’s fine. Only that no indication is given, that the callee is still listening.
The second time, i think, i closed it while trying to open the settings dialog to adjust the over-driven microphone. That’s fine, too, since one may for instance want to check the mail for a invoice number or so during a call. Problem is, that one cannot actively disconnect anymore once the phone app is closed.
I was not able to find a good work-around yet, that allows to close the connection in that state. It can best be terminated remotely. I dialed again in that state though and found the phone dialog then in the right state again though, but now with two connections, which i could close both.
My suspicion is, that the phone app does not check the status of the modem when started and therefor does not present a hang-button.
Also, an indication of on-going calls in the status bar would be helpful to clearly indicate the state.
It is not possible to get into this state, when receiving an incoming call while the phone is locked. In this situation, the up-arrow is not available.
Hope it helps.