Customer reported that 7810 phones make a sound for a second at irregular intervals. For firmware V100R001C03SPC100 the issue is present.
They have multiple phones in the office, all 7810 model and they make the sound at random intervals while being in idle status.
A call shortly before or after the event occurs doesn't influence the sound trigger.
The following steps were taken in handling this issue:
1. Requested phone logs from the customer and there was no information present about the strange sound.
2. Requested a network capture to see if any signaling is being sent from the PBX to the phone and we could not find anything out of the ordinary.
3. Since the issue could not be related to register process, calling, missing a call or voice mail message, a firmware upgrade has been proposed and they confirmed that the issue has been fixed.