This is most likely malicious scanning software connecting directly to the SIP device thinking that it is a PBX. It is generally not dangerous but can be a nuisance. To prevent this, the SIP device should be behind a router/firewall and not using port 5060-5061 on the WAN side of the router.
Some SIP devices have a feature to disable direct inbound IP calling and/or anonymous calling. The name given to this feature varies depending on the SIP device manufacturer.
For example:
For Grandstream GXP1400, disable the feature they call Direct IP calling.
From the phone menu:Settings > Call Features > Disable Direct IP Call > Yes
Extension rings but nobody is there. Caller ID may be an extension number that does not exist on the PBX. Nothing in the PBX call history report.
- ring, silent, random, extension, device, report
