Can a caller tell the difference between a POTS phone and a VOIP phone?

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Jeff Layman

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Apr 7, 2021, 7:30:24 AM4/7/21
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It's been ages since the last one, but I've just had of a couple of
"Openreach" scam calls (Indian voice, South Korea code). I wondered if
it was possible for the caller to know if the phone they were calling
was an old analogue landline or VOIP phone.

If they can't, it wastes their time as an analogue line might have no
router connected (which is what the scam caller told me was having a
problem connecting to the internet), so they can't connect to any
computer connected to it. With a VOIP phone, if it can be identified as
such, there must be a router on that line, so it would be useful to
note that number for a future scam call. I know that it won't be that
long before we are all VOIP connected, but was just interested in the
question. Is there some code the caller can use to identify a POTS phone?

--

Jeff

Theo

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Apr 7, 2021, 10:57:03 AM4/7/21
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Jeff Layman <jmla...@invalid.invalid> wrote:
> It's been ages since the last one, but I've just had of a couple of
> "Openreach" scam calls (Indian voice, South Korea code). I wondered if
> it was possible for the caller to know if the phone they were calling
> was an old analogue landline or VOIP phone.

They can tell whether the number prefix is allocated to Openreach/BT,
Virgin, Sky, etc, or to another provider like Magrathea. The latter are
likely to be third-party VOIP.

Without an inside connection to the number-owning provider they can't tell
where the traffic is going, and whether you've ported a number to VOIP.
Although there might be ways to fingerprint the signalling or audio that
comes out of such a line, but they would have to call it first.

> If they can't, it wastes their time as an analogue line might have no
> router connected (which is what the scam caller told me was having a
> problem connecting to the internet), so they can't connect to any
> computer connected to it. With a VOIP phone, if it can be identified as
> such, there must be a router on that line, so it would be useful to
> note that number for a future scam call. I know that it won't be that
> long before we are all VOIP connected, but was just interested in the
> question. Is there some code the caller can use to identify a POTS phone?

I'd say it's the opposite of that. With an Openreach number they know you
have xDSL or OR FTTP. With a VOIP number they don't know what kind of
connection you have - maybe you're in the office of MegaCorp or using
the wifi in Starbucks. They therefore can't spin a story that fits your
situation because they have less information about that situation.

Theo

Jeff Layman

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Apr 7, 2021, 11:31:34 AM4/7/21
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I don't understand that. I have ex-directory BT number and a POTS line
(with FTTC). How can they know I have xDSL/FTTP or not? Is there some
tone/signal/code they can send which can identify anything other than a
POTS phone at the other end? And from your first paragraph above, if
they can identify it's a number allocated to Openreach/BT rather than
one of the "digital" companies, there must still be many old BT
customers who have no router connected, so if they continue with trying
to scam one of those particular lines they are wasting their time.

--

Jeff

notya...@gmail.com

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Apr 7, 2021, 3:29:34 PM4/7/21
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You can look up any UK number and see whom it was originally allocated to, but not if it has been ported out.

I have two adjacent landline numbers - one is still BT with FTTC and the other is with Voipfone. About the only way to tell is that the audio quality is better on the VOIP line. AFAIK they can't tell whether there is DSL on a line - probably the most frequent scam call I get is from "BT Openreach" about to cut off my internet. These come on the line with FTTC, the VOIP number and on another BT line without DSL AFAICT indiscriminately.

Most scam calls these days use spoofed UK numbers. The will use non existent number ranges, disconnected lines and more recently mobile numbers. Very occasionally they use real numbers, probably inadvertently (e.g. a firm of solicitors in one case), but one used another nearby resident's and another my own number!

Theo

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Apr 8, 2021, 9:31:11 AM4/8/21
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Jeff Layman <jmla...@invalid.invalid> wrote:
> I don't understand that. I have ex-directory BT number and a POTS line
> (with FTTC). How can they know I have xDSL/FTTP or not? Is there some
> tone/signal/code they can send which can identify anything other than a
> POTS phone at the other end? And from your first paragraph above, if
> they can identify it's a number allocated to Openreach/BT rather than
> one of the "digital" companies, there must still be many old BT
> customers who have no router connected, so if they continue with trying
> to scam one of those particular lines they are wasting their time.

Such scams work in bulk, and people without broadband are small enough to be
collateral damage.

Let's look at 01234 on CodeLook:
https://www.telecom-tariffs.co.uk/codelook.htm

Number Locality or Use Service Charging Operator
Number Status

01234 21 Bedford, Bedfordshire Geographic BT B1
National British Telecom Allocated

01234 31 Bedford, Bedfordshire Geographic Cable B1
National Virgin Media Allocated

01234 97 7 Bedford, Bedfordshire Geographic Virtual B1
National ICUK Computing Services Allocated
01234 97 8 Bedford, Bedfordshire Geographic Virtual B1
National Belgacom International Carrier Services SA Allocated
01234 97 9 Bedford, Bedfordshire Geographic Virtual B1
National SiPalto Allocated

If I'm a scammer, I don't need to bother with numbers that are 'Geographic
Virtual' because they're VOIP or something similar. While Geographic BT are
going to be physical Openreach connections (unless ported, which is
impossible to determine) and Geographic Cable will be that.

So I program my system to ring the Geographic BT people with the 'hello
we're BT Openreach disconnections' message, the Geographic Cable people with
'hello we're Virgin Media disconnections' and I don't call the Geographic
Virtual people at all. By skipping the Virtual ranges I can whittle down
the number of calls I need to make quite a bit (these calls cost money when
made in this quantity).

Next up, if I'm a smart scammer I play everyone a recorded message with the
story and ask them to press 1. This filters out answering machines and
people who don't fall for the scam. Now I have a nice feed of
higher grade marks I can get my scammer call centre to answer.

Theo

Jeff Layman

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Apr 9, 2021, 4:57:39 AM4/9/21
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Most interesting. Thanks for the lesson!



--

Jeff

notya...@gmail.com

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Apr 10, 2021, 12:10:18 PM4/10/21
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So I usually press 1, say hello and then either ignore the teletubbie, or bait them a for a bit.

Woody

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Apr 10, 2021, 2:13:35 PM4/10/21
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And in doing so you have proved the line is used by a real person
probably at home so your number becomes a tradable commodity in their world.

Ergo, never answer if you don't recognise the number, and after it has
ended block it either on your own phone or via BT Privacy.

Doesn't stop 'em though!


notya...@gmail.com

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Apr 11, 2021, 8:27:36 AM4/11/21
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On Saturday, 10 April 2021 at 19:13:35 UTC+1, Woody wrote:
> On Sat 10/04/2021 17:10, notya...@gmail.com wrote:
> > On Thursday, 8 April 2021 at 14:31:11 UTC+1, Theo wrote:
SNIP
> >> Next up, if I'm a smart scammer I play everyone a recorded message with the
> >> story and ask them to press 1. This filters out answering machines and
> >> people who don't fall for the scam. Now I have a nice feed of
> >> higher grade marks I can get my scammer call centre to answer.
> >>
> >> Theo
> >
> > So I usually press 1, say hello and then either ignore the teletubbie, or bait them a for a bit.
> >
> And in doing so you have proved the line is used by a real person
> probably at home so your number becomes a tradable commodity in their world.

Well as both of mine are in the phone book anyway...

OTOH spam and scam calls to my mobile are fairly infrequent and are probably mostly because it is in the original 0[7]860 so scammers know holders have probably had a mobile for decades and since they cost ££££.

>
> Ergo, never answer if you don't recognise the number, and after it has
> ended block it either on your own phone or via BT Privacy.
>
> Doesn't stop 'em though!

No and these days they usually ring back on a different number. Current fashion is to call from dud mobile numbers - do I know all my contacts' mobile numbers? Not a chance.

Michael Chare

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Apr 19, 2021, 7:25:13 PM4/19/21
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On 11/04/2021 13:27, notya...@gmail.com wrote:
> On Saturday, 10 April 2021 at 19:13:35 UTC+1, Woody wrote:
>> On Sat 10/04/2021 17:10, notya...@gmail.com wrote:
>>> On Thursday, 8 April 2021 at 14:31:11 UTC+1, Theo wrote:
> SNIP
>>>> Next up, if I'm a smart scammer I play everyone a recorded message with the
>>>> story and ask them to press 1. This filters out answering machines and
>>>> people who don't fall for the scam. Now I have a nice feed of
>>>> higher grade marks I can get my scammer call centre to answer.
>>>>
>>>> Theo
>>>
>>> So I usually press 1, say hello and then either ignore the teletubbie, or bait them a for a bit.
>>>
>> And in doing so you have proved the line is used by a real person
>> probably at home so your number becomes a tradable commodity in their world.
>
> Well as both of mine are in the phone book anyway...
>
> OTOH spam and scam calls to my mobile are fairly infrequent and are probably mostly because it is in the original 0[7]860 so scammers know holders have probably had a mobile for decades and since they cost ££££.
>
>

I had some of these calls to a mobile recently. The first 8 digits of
the calling number where the same as that of my mobile. Only the last
three digits were different. I did wonder why the bothered to do this.


--
Michael Chare

David Woolley

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Apr 20, 2021, 6:22:03 AM4/20/21
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On 20/04/2021 00:25, Michael Chare wrote:
> I had some of these calls to a mobile recently. The first 8 digits of
> the calling number where the same as that of my mobile. Only the last
> three digits were different.  I did wonder why the bothered to do this.
>

In the US, and also in China, mobile numbers are allocated
geographically. At least in America, there were lots of local
operators. Callers got charged as though calling a landline, the mobile
user picked up the terminating air time cost.

The caller may not know that +447 represents non-geographical numbers,
and assume that similar numbers are locally to be those of nearby
people, and therefore more trustworthy.

Owain Lastname

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Apr 22, 2021, 2:39:58 PM4/22/21
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On Tuesday, 20 April 2021 at 00:25:13 UTC+1, Michael Chare wrote:
> I had some of these calls to a mobile recently. The first 8 digits of
> the calling number where the same as that of my mobile. Only the last
> three digits were different. I did wonder why the bothered to do this.

It's an established technique for scammers and debt collectors - it assumes people are more likely to answer a local number as it could be a neighbour, plumber, someone calling about the card in the newsagent's window advertising kittens, etc.

Owain

Brian Gregory

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May 9, 2021, 9:23:00 PM5/9/21
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On 07/04/2021 16:31, Jeff Layman wrote:
> I don't understand that. I have ex-directory BT number and a POTS line
> (with FTTC). How can they know I have xDSL/FTTP or not? Is there some
> tone/signal/code they can send which can identify anything other than a
> POTS phone at the other end? And from your first paragraph above, if
> they can identify it's a number allocated to Openreach/BT rather than
> one of the "digital" companies, there must still be many old BT
> customers who have no router connected, so if they continue with trying
> to scam one of those particular lines they are wasting their time.

So what?
They don't mind wasting a bit of time as long as one or two people get
scamming into paying.

--
Brian Gregory (in England).

Brian Gregory

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May 9, 2021, 9:25:00 PM5/9/21
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On 10/05/2021 02:22, Brian Gregory wrote:
> So what?
> They don't mind wasting a bit of time as long as one or two people get
> scamming into paying.
>

*scammed
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