Hi, I am using a TP-link VOIP modem to access the open vfx phone service.

It seems that at least (approx) once a week the phone "dies", without our knowledge at seemingly random times.

Definition of dies is:

Picking up handle of the phone there is an echo, as if the phone is on hook / Sometimes however, there is still a dial tone.
Dialing out does not work. Not connection attempted
Dialing in, calls are reverted straight to voicemail

The line will never self liven.

Any ideas of settings I could be checking to stop this frequent behaviour?

Side question:

Regarding voicemail when the phone is under normal operation, Is there something that can be done (again setting to check that are in place) to get the alternate dial tone when picking up the receiver and voicemail is present? as what the case when I was on VFX certified?