@Kain_W
Please raise a ticket & post the ticket number back to this thread.
Feel free to use these words.
VOIP Ghost Calls / Direct IP Calls (SPIT)
Customers suffering this issue should note that this is not a traditional call to your telephone number, don’t inconvenience yourself by requesting a number change. The lack of a ring signal may be the only thing preventing customers being spoken to by a spam/scam caller.
From the customer’s perspective connecting a telephone instrument to an RJ11 socket of a Hub(3/4/5) is using an analogue telephone service and it is quite reasonable to expect a similar fuss free telephone service.
From Virgin Media’s perspective they are a VOIP operator, with responsibility for the service operation including customer line security.
The current situation of customers receiving calls that present on telephones with a blank caller id and no ring tone are Direct IP calls made to the customer’s public IP address on port 5060 the default in bound SIP port. A Direct IP call could be from a true VOIP phone but far more likely it is bulk calls from a computer script to xxx.xxx.xxx.xxx:5060 the public IP address of the Hub.
VM Hubs have SIP ALG enabled and from what we see have inbound Direct IP call answer enabled, but do not appear to have a ring cadence pattern set for this call type, hence the call is silent.
VOIP providers usually advise customers how to avoid being exposed to Direct IP calls from the public internet so as to avoid nuisance calls.
Virgin Media might like to consider implementing the most common and effective approaches to preventing Direct IP calls, these are either HUB ATA firmware changes and/or VOIP platform changes…
Disable Direct IP calls (Hub)
Only permit genuine telephone calls via the registered SIP proxy, i.e. restrict in bound and out bound calls to those that will be shown on customer bills.
Use a non-standard SIP ports (Hub & VOIP platform)
Change the UDP ports number to remove the known in bound attack surface at UDP 5060.
Disable SIP ALG (Hub)
To stop routing uninvited UDP 5060 SIP traffic from the public internet to the HUB’s Analogue Telephone Adaptor.
