Phantom Rings occurring when picking up a call?



UCM6202 - GXP2170 phones all POE Latest firmware

Very random like once every couple of weeks.

Call comes in through SIP provider to the main ring group.

When Users pick up the phone to answer the call other random phones start ringing indefinitely until the user walks over to the phone to pick it up. Sometimes it doesn’t happen until the user parks the call. When this happens there is nothing on the display showing the number coming in, it just shows that the lines are ringing.

Also when the user picks up the phantom ring and listens to the handset. All they hear is ringing in the handset.

They have to walk around to each random phone and pick it up and hangup to make the phones stop ringing.

Remote users on the system are not getting the phantom Rings.

Any ideas?

Appreciate your input.



Likely cause is one of two things.

Option 1:
Phones are picking up network traffic and processing it as a call.
The fix is a phone setting:
Account X(probably 1)–>SIP Settings–>Security settings
2) Check SIP User ID for Incoming INVITE: Yes

If you prefer to provision:
P258 = 1

Option 2:
outside hackers spamming your system(though less likely, is still possible)


Settings are the same.

But I tracked down the number at the time they called.

It was questionable. As well as the call conversation itself.

Can hackers be calling in an attempt to open ports while they are scanning?


Thanks for the help.



I agree @lstutesman , I find it strange, but that the “hackers” wake up every 15 days :slight_smile:

@lstutesman I take advantage of this for a question, I took a look at P258 (Check SIP User ID for incoming INVITE) exactly what it is for and it is advisable in normal operation to set it to YES or NO?


however, for safety reasons, it is always better to use an AuthID different from the user (which, as far as I can see, very few people do).
Never forgetting the ACLs on the firewall.


It is definitely more secure to change it, however with more security means more management.