I have the BT6510 Nuisance Call Blocker and today an unwanted call got through!
When I looked at the Calls Log menu the call was listed as No Number! What is the difference between No Number, Unavailable and Caller ID withheld? Have the spammers found a way around BT system? Is this just a local exchange one off fault? Will the firmware in all BT's Nuisance Call Blocker products need updating?
I tried to use the email function to contact BT but got an internal server error! God only knows what BT does with all its profits!
Probably simply a corrupted caller ID signal. It can happen if there is noise or interference on the line. If the error check on the CLI data burst fails the CRC check, then it will be rejected, and the phone will display "no number".
Possible corrupt CLI data but this is the answer I received from BT:
"Please note that the BT 6510 is purely reliant on the telephone line to display the caller display. In case of some calls for example VOIP calls, the caller has access to the definition of number and text they present themselves as. The only way the product would be displaying “No Number” during an incoming call is when this is the actual text received within the Caller display that was sent by the originating party. There is no provision in the network to be able to distinguish VOIP calls by “type".
This is the reason why the BT6510 is guaranteed to block up to 80% if the nuisance calls. Some calls may still come through I am afraid."
So it may have also been a VOIP call that sent alphanumeric text in place of a number, if so this is a way to bypass the blocking solution of devices such as the BT6510. Yet a simple alteration to the BT6510 software could block all caller ID where text is sent or allow the addition to the blocked list alphanumeric text rather than just numeric numbers.
Well just had another reply to my questions about the blocking of No Number (VOIP originated) calls and this is the message:
"There are no plans to update the 'firmware' on the BT 6510.
You may be able to block 'NO NUMBER' calls at the exchange via a variant of your line providers Anonymous Call Reject service. (If your line provider is BT call 0800 800 151 - Line services)."
So we have to pay for additional exchange blocking as their phone, designed for this purpose, can't manage it! I would urge BT to be honourable and offer a free firmware fix for the BT6510 Nuisance Call Blocker and other similar products and stop gouging their customers.
Truecall will definitely block anything you want to block, I'm sure someone who uses a CPR blocker can tell you whay that can block.
Much ,much better that a telephone like the 6510,7600 or variants , with a lot more options.