Withholding caller ID on Zen Digitial Voice

[Geoff Clare]

According to this page on Zen's website:

https://www.zen.co.uk/help-support/analogue-phone-number-withholding-setup

I should be able to prefix a number with *31# to withhold caller ID,
but it's not working for me. (I called my mobile using the prefix
and it showed that my home number was calling.)

The page also gives instructions for how to set the default to
withheld, so I tried that too but with the same result.

Anyone else on Zen Digital Voice (and using their supplied Fritzbox)
having the same problem, or is it just me?

--
Geoff Clare <net...@gclare.org.uk>

[Woody]

Have you tried preceding the number with 141 - the usual short code to
withhold CLI?

[grinch]

I wonder,I could be adding 2 + 2 and getting 5 here, but Ofcom have told
telephone providers they must do more to stop spam/scam calls.

If you always send CLI regardless of the end users router settings this
would probably comply with that edict from Ofcom.

You could ask Zen to turn off cli if you want to be ex-directory

Just guessing here

[David Wade]

On 28/11/2022 17:33, grinch wrote:
> On 28/11/2022 16:56, Woody wrote:
>> On Mon 28/11/2022 13:47, Geoff Clare wrote:
>>> According to this page on Zen's website:
>>>
>>> https://www.zen.co.uk/help-support/analogue-phone-number-withholding-setup
>>>
>>> I should be able to prefix a number with *31# to withhold caller ID,
>>> but it's not working for me.  (I called my mobile using the prefix
>>> and it showed that my home number was calling.)
>>>
>>> The page also gives instructions for how to set the default to
>>> withheld, so I tried that too but with the same result.
>>>
>>> Anyone else on Zen Digital Voice (and using their supplied Fritzbox)
>>> having the same problem, or is it just me?
>>>
>>
>> Have you tried preceding the number with 141 - the usual short code to
>> withhold CLI?
>
> I wonder,I could be adding 2 + 2 and getting 5 here, but Ofcom have told
> telephone providers they must do more to stop spam/scam calls.
>

Withheld isn't usually a problem. Generally that is a UK public service
say NHS/Local Council/government department with an antique system that
can only generate a single fixed CLI for the whole organization.

Its spoofed CLI that are a problem.

> If you always send CLI regardless of the end users router settings this
> would probably comply with that edict from Ofcom.
>

nope

> You could ask Zen to turn off cli if you want to be ex-directory
>
> Just guessing here

I don't think so.


Dave

[Brian Gregory]

On 28/11/2022 13:47, Geoff Clare wrote:

I think their website and help video are wrong.

Try #31# instead. That would be the more usual code for withhold number.
For instance #31# works for withold number on many mobile networks.

--
Brian Gregory (in England).

[Geoff Clare]

The Fritzbox manual agrees with Zen's website (*31#). Anyway, I have
now tried #31# in case they're both wrong, and it didn't work.

--
Geoff Clare <net...@gclare.org.uk>

[Geoff Clare]

No, I didn't think of that. I assumed that the old way only worked
with "old technology". I have tried it now and - it works!

Thanks.

--
Geoff Clare <net...@gclare.org.uk>

[Brian Gregory]

Clearly Zen have made of mess of this.

[Brian Gregory]

But the call does go through with *31# or #31# prepended to the number?

[grinch]

On 29/11/2022 17:07, Brian Gregory wrote:
>
>>>
>>> Try #31# instead. That would be the more usual code for withhold number.
>>> For instance #31# works for withold number on many mobile networks.
>>
>> The Fritzbox manual agrees with Zen's website (*31#). Anyway, I have
>> now tried #31# in case they're both wrong, and it didn't work.
>>
>
> But the call does go through with *31# or #31# prepended to the number?
>

We are assuming here that the cli presented to the called party is
generated by your local router,it may be coming from the Zen VoIP server
voip2.zen.co.uk.

As I said before to prevent spoofing as dictated by Ofcom ??

[Geoff Clare]

Brian Gregory wrote:

> On 29/11/2022 13:52, Geoff Clare wrote:
>> Woody wrote:
>>
>>> On Mon 28/11/2022 13:47, Geoff Clare wrote:
>>>> According to this page on Zen's website:
>>>>
>>>> https://www.zen.co.uk/help-support/analogue-phone-number-withholding-setup
>>>>
>>>> I should be able to prefix a number with *31# to withhold caller ID,
>>>> but it's not working for me. (I called my mobile using the prefix
>>>> and it showed that my home number was calling.)

>>> Have you tried preceding the number with 141 - the usual short code to
>>> withhold CLI?
>>
>> No, I didn't think of that. I assumed that the old way only worked
>> with "old technology". I have tried it now and - it works!

> Clearly Zen have made of mess of this.

I wonder whether this is a recent change to their VoIP system and
they haven't yet updated their website to match.

--
Geoff Clare <net...@gclare.org.uk>

[Geoff Clare]

grinch wrote:

> On 29/11/2022 17:07, Brian Gregory wrote:
>>
>>>>
>>>> Try #31# instead. That would be the more usual code for withhold number.
>>>> For instance #31# works for withold number on many mobile networks.
>>>
>>> The Fritzbox manual agrees with Zen's website (*31#). Anyway, I have
>>> now tried #31# in case they're both wrong, and it didn't work.
>>>
>>
>> But the call does go through with *31# or #31# prepended to the number?

Yes, but always with caller ID shown to the callee.

> We are assuming here that the cli presented to the called party is
> generated by your local router,it may be coming from the Zen VoIP server
> voip2.zen.co.uk.

I don't think that would make any difference.

With the old PSTN system the caller's ID is always transmitted as far
as the callee's exchange and there is a flag which tells that exchange
whether to present (CLIP) or withhold/restrict (CLIR) the caller's ID.
I assume something similar happens with mobiles and with VoIP. I was
calling my mobile, so the problem seems to be that the "exchange" (or
whatever the mobile equivalent is) that calls my mobile isn't being
told to withhold my ID.

--
Geoff Clare <net...@gclare.org.uk>

[Woody]

OR the CLIR is not being forwarded from the PSTN system to the mobile
operator?

[grinch]

On 30/11/2022 13:35, Geoff Clare wrote:
> grinch wrote:
>

er
>> voip2.zen.co.uk.
>
> I don't think that would make any difference.
>
>

> calling my mobile, so the problem seems to be that the "exchange" (or
> whatever the mobile equivalent is) that calls my mobile isn't being
> told to withhold my ID.
>

Assuming you are correct which I think you are, that would solve the
problem of the Ofcom edict to prevent number spoofing.

You can't turn the cli off even if you want to,unless you ask Zen to
become ex-directory and then its probably not transmitted in the first
place.

Speak to Zen directly but I would not be surprised if you only get a
permanently on or off cli option.

[Geoff Clare]

grinch wrote:

> Speak to Zen directly but I would not be surprised if you only get a
> permanently on or off cli option.

Did you miss my post in this thread where I said that 141 works?

I sent them an email reporting that the methods described on their
website don't work but 141 does, suggesting that perhaps this had
changed on their VoIP system but the website had not caught up.
I got a response that they would forward the information to the
website team (but without actually saying my guess was right, so
that remains to be seen if/when the web page is updated).

--
Geoff Clare <net...@gclare.org.uk>

[grinch]

Or is it the called parties " exchange " that is blocking it and Zen is
sending it ??

You could sniff the outgoing packets to find out but as you have got the
result you want why bother.

[grinch]

On 01/12/2022 13:54, Geoff Clare wrote:
> grinch wrote:
>
>> Speak to Zen directly but I would not be surprised if you only get a
>> permanently on or off cli option.
>
> Did you miss my post in this thread where I said that 141 works?

No I understood that but it is not likely that its your router is
withholding the cli but further up the chain between calling and called
parties. Given that 141 is not the correct command according to the
router manufacturer.

Its 25 years since I worked on PSTN equipment but 141 would cause a
SystemX exchanges to withhold the cli and I thought it was UK wide
irrespective of the make of the exchange .

I also think I remember it was withheld at the called parties local
exchange not the calling party local exchange.

So it may be the called parties exchange that is withholding the cli not
your router,which is what I said.

>
> I sent them an email reporting that the methods described on their
> website don't work but 141 does, suggesting that perhaps this had
> changed on their VoIP system but the website had not caught up.
> I got a response that they would forward the information to the
> website team (but without actually saying my guess was right, so
> that remains to be seen if/when the web page is updated).
>

It is most likely a correct command and without packet sniffing the
outgoing data you cant be certain.

If you are correct that it makes no difference then they should put on
the website, that " the way our system is configured it make no
difference what you set your router to cli wise".

But as I said it works the way you want it to ,not just how you thought
it would.

[Brian Gregory]

On 01/12/2022 13:54, Geoff Clare wrote:

I started to discuss this with Zen in Youtube comments but I really need
you to be there to confirm everything for sure for the discussion to
continue.
This is the video: https://youtu.be/5bbHfuoZUXk

[Geoff Clare]

I have replied there. I included a new piece of information that I
noticed recently, which is that another Zen web page at
https://www.zen.co.uk/phone/digital-voice/
says (under "What’s included ...") "Dial 141 before a call to prevent
the other party from seeing your phone number".

--
Geoff Clare <net...@gclare.org.uk>