If you notice that the ringer stops working when using the V350, you'll need to run a test on the equipment. To do so, you'll need to place the outdoor panel next to the monitor.
To connect it, you can use two 5mm² electrical wires. A short length is sufficient for this test (less than one meter).
If the ringing is restored, it's a local problem. Verify the following:
For other cases and if the equipment continues with this error, contact Somfy's consumer service.