Phantom Calls From SIP Trunk

[Drew9213]

I've got a client running 3CX version 15 and they are getting random phantom calls from their SIP trunk. Calls come in normally and display the correct caller ID, but at random times they will get a call with "trunk" as the caller ID and the call log shows the call coming from the SIP trunk. When answered these calls just produce a dead line.

 

[leejor]

It may be someone (hacker?) attempting a direct SIP call. Does the log show any sent digits? Do they originate from one IP?

If they continue, and they seem to be coming from one source, you can blacklist the IP (or range), or perhaps enlist the help of your VoIP provider to block the calls.

 

[JasonNadeau]

Yeah it sounds like a direct Sip call, but seems like those go right to the phone usually, not through the sip provider.
Are they Yealink phones ?

 

[leejor]

If it is coming from your VoIP provider, it might be a "marketing" call with a blocked number. A lot of those, being automated, can have a delay before the "computer" comes on the line. In that case i would see if there is any sort of trace that can be done by your provider. they may , at least be able to determine if the call comes to them from the same destination, then forward the complaint to the originator for investigation.