DTMF and making a
Archiver
Posts: 46,084
I had a brief search through the message archive but couldnt find
anything :-(
I'm looking to make, by way of an experiment - that will never be
attached to the real phone line ;-) - a phone call barring unit.
A stamp (BS2-IC) would seem to be a perfect basis for this and I've
come up with some ideas for this based on a couple of DTMF decoder
circuits I have found.
Any ideas on the project, likely snags ???
Advice always welcome.
David
anything :-(
I'm looking to make, by way of an experiment - that will never be
attached to the real phone line ;-) - a phone call barring unit.
A stamp (BS2-IC) would seem to be a perfect basis for this and I've
come up with some ideas for this based on a couple of DTMF decoder
circuits I have found.
Any ideas on the project, likely snags ???
Advice always welcome.
David
Comments
>I had a brief search through the message archive but couldnt find
>anything :-(
>
>I'm looking to make, by way of an experiment - that will never be
>attached to the real phone line ;-) - a phone call barring unit.
>
>A stamp (BS2-IC) would seem to be a perfect basis for this and I've
>come up with some ideas for this based on a couple of DTMF decoder
>circuits I have found.
>
>Any ideas on the project, likely snags ???
>
>Advice always welcome.
>David
I can't speak for the UK, but I can buy a Caller-ID unit with specific call
blocking, as well as blocked-ID blocking, here in the US cheaper than I can
buy a BS2-IC, caller-Id decoder chip, and a board with supporting parts to
mount them on. The drawback is that I must receive the first call before I
can block later calls from the same number. With a BS2-IC based device you
could enter numbers in advance of ever being called by them and you could
choose to answer and hang up, answer and play a recorded message (a
solid-state voice chip comes to mind here), or not answer at all. You
could do the latter without passing the ringing signal on to an answering
machine or other phones in series with the BS2 device so it would appear
you weren't home, but you wouldn't have to hear any rings after the first.
Anyhow, what you want can be found at
http://home.earthlink.net/~jgsparks/ee/programs.html
BS2 programs and circuit diagrams here.
Jim H
modems.
Ideally what you want to do is put the blocking unit upstream of all the
phones, then block the first and second ring from the phones until the
caller ID info can be read and verified. Then let the subsequent rings go to
the phones.
Original Message
> >I had a brief search through the message archive but couldnt find
> >anything :-(
> >
> >I'm looking to make, by way of an experiment - that will never be
> >attached to the real phone line ;-) - a phone call barring unit.
> >
> >A stamp (BS2-IC) would seem to be a perfect basis for this and I've
> >come up with some ideas for this based on a couple of DTMF decoder
> >circuits I have found.
> I can't speak for the UK, but I can buy a Caller-ID unit with specific
call
> blocking, as well as blocked-ID blocking, here in the US cheaper than I
can
> buy a BS2-IC, caller-Id decoder chip, and a board with supporting parts to
> mount them on. The drawback is that I must receive the first call before
I
> can block later calls from the same number. With a BS2-IC based device
you
> could enter numbers in advance of ever being called by them and you could
> choose to answer and hang up, answer and play a recorded message (a
> solid-state voice chip comes to mind here), or not answer at all. You
> could do the latter without passing the ringing signal on to an answering
> machine or other phones in series with the BS2 device so it would appear
> you weren't home, but you wouldn't have to hear any rings after the first.
>Not to mention there are shareware Windoze programs that work with caller-ID
>modems.
>
>Ideally what you want to do is put the blocking unit upstream of all the
>phones, then block the first and second ring from the phones until the
>caller ID info can be read and verified. Then let the subsequent rings go to
>the phones.
The caller-Id info seems to come in either on the first ring or between the
first and second rings. No need to block the second ring unless processing
of the CID info is very slow.
Jim H
> I had a brief search through the message archive but couldnt find
> anything :-(
>
> I'm looking to make, by way of an experiment - that will never be
> attached to the real phone line ;-) - a phone call barring unit.
>
> A stamp (BS2-IC) would seem to be a perfect basis for this and I've
> come up with some ideas for this based on a couple of DTMF decoder
> circuits I have found.
>
> Any ideas on the project, likely snags ???
>
> Advice always welcome.
> David
Sorry .. perhaps I didnt make it clear that I want to bar outgoing
calls, not incoming.
Two groups immediatly spring to mind - 07xx (calls to Mobiles) and
089xx (Premium rate numbers).
I figure that if I look for sequences starting 0 and then have a
variable length table lookup for the barred area/service codes. If
they enter a code that is barred then it starts a timer and they have
to follow it up with a PIN (say *nnnn) or it drops the line (goes
OnHook) after (say) 60 secs.
I'd need some logic to ignore caller ID codes - ignore tones between
ring signals ?
David
not to post until I got a view on how the group works. Unfortuanatly
this is just a far to interesting suject to keep my nose out of [noparse]:)[/noparse]
> Sorry .. perhaps I didnt make it clear that I want to bar outgoing
> calls, not incoming.
I don't think the hardware side will cause you too many problems.
what facinates me is the logic side of it.
> Two groups immediatly spring to mind - 07xx (calls to Mobiles) and
> 089xx (Premium rate numbers).
My solution would be to look at it from the other side. Because of
the now integrated nature of the telephone service,there are only two
numbers of interest to you and they are the first two.
So in a lookup table
1ST 2ND ACTION
0 1 No Action (prefix for national codes)
0 2 No Action (prefix for city codes)
0 8 No Action (Confusingly)
0 ANYOTHER Hang up
1-9 ANY No action (local number)
* wait for pin code
NOTE:- you MUST not allow 00 because .....
09789 243 243 (Madam Fifi's line of naughtiness)
is exactly the same as
00 44 9789 243 243
The integrated numbering is here ...
http://www.numberchange.org/business/index.php3?section=1
> I figure that if I look for sequences starting 0 and then have a
> variable length table lookup for the barred area/service codes.
If
> they enter a code that is barred then it starts a timer and they
have
> to follow it up with a PIN (say *nnnn) or it drops the line (goes
> OnHook) after (say) 60 secs.
When the program his a banned number I think it should hang up
straight away. Also if it only last 60 seconds you have still paid
for the connection of the call. Also if you call someones mobile
and they pick up staight away they will get Codes in their ear.
Perhaps a better way to do it would be to enter the code before the
call. On recieveing the code the call barring would be suspended
for the next call only like this ...
Pickup reciever ..
Dial *1234 (code)
Telephone service response "This number has not been recognised
Please hang up and try again"
Hang up
Dial 09789 243 243
Also what would happen if someone connected a pulse (dial)phone to
the system ? You would have to have some way of detecting that and
dropping the line straight away.
I don't think that the CLID codes will be a problem as your logis
will only be interested in out going calls and only be active if the
phone is "Off Hook" ..
Top Project BTW [noparse]:)[/noparse]
Justin
give you a fake dialtone, you punch in the number, the system looks for a
long period with no keypresses, then checks the number and dials it for you.
Original Message
> I don't think the hardware side will cause you too many problems.
> what facinates me is the logic side of it.
>
> > Two groups immediatly spring to mind - 07xx (calls to Mobiles) and
> > 089xx (Premium rate numbers).
>
> My solution would be to look at it from the other side. Because of
> the now integrated nature of the telephone service,there are only two
> numbers of interest to you and they are the first two.
>
> So in a lookup table
>
> 1ST 2ND ACTION
> 0 1 No Action (prefix for national codes)
> 0 2 No Action (prefix for city codes)
> 0 8 No Action (Confusingly)
> 0 ANYOTHER Hang up
> 1-9 ANY No action (local number)
> * wait for pin code
>
> NOTE:- you MUST not allow 00 because .....
>
> 09789 243 243 (Madam Fifi's line of naughtiness)
>
> is exactly the same as
>
> 00 44 9789 243 243
>
>
> The integrated numbering is here ...
> http://www.numberchange.org/business/index.php3?section=1
>
> > I figure that if I look for sequences starting 0 and then have a
> > variable length table lookup for the barred area/service codes.
> If
> > they enter a code that is barred then it starts a timer and they
> have
> > to follow it up with a PIN (say *nnnn) or it drops the line (goes
> > OnHook) after (say) 60 secs.
>
> When the program his a banned number I think it should hang up
> straight away. Also if it only last 60 seconds you have still paid
> for the connection of the call. Also if you call someones mobile
> and they pick up staight away they will get Codes in their ear.
>
> Perhaps a better way to do it would be to enter the code before the
> call. On recieveing the code the call barring would be suspended
> for the next call only like this ...
>
> Pickup reciever ..
>
> Dial *1234 (code)
> Telephone service response "This number has not been recognised
> Please hang up and try again"
> Hang up
> Dial 09789 243 243
>
>
>
>
> Also what would happen if someone connected a pulse (dial)phone to
> the system ? You would have to have some way of detecting that and
> dropping the line straight away.
>
> I don't think that the CLID codes will be a problem as your logis
> will only be interested in out going calls and only be active if the
> phone is "Off Hook" ..
> I think what you need to do is what commercial telephone systems
do -- they
> give you a fake dialtone, you punch in the number, the system looks
for a
> long period with no keypresses, then checks the number and dials it
for you.
I disagree, I don't think it's that complicated. The only important
digits are the first two on on the basis of that information the unit
can decide whether to continue the call or not.
relay) have a tone decoder chip monitor the line if 976 is dialed then the
stamp open's the relay and turn's off the phone, stays off until manual
reset or time delay reset.
Original Message
From: <justin@k...>
To: <basicstamps@yahoogroups.com>
Sent: July 21, 2001 3:18 PM
Subject: [noparse][[/noparse]basicstamps] Re: DTMF and making a "call barring" unit for a UK
telephone
| --- In basicstamps@y..., Rodent <daweasel@s...> wrote:
| > I think what you need to do is what commercial telephone systems
| do -- they
| > give you a fake dialtone, you punch in the number, the system looks
| for a
| > long period with no keypresses, then checks the number and dials it
| for you.
|
| I disagree, I don't think it's that complicated. The only important
| digits are the first two on on the basis of that information the unit
| can decide whether to continue the call or not.
|
|
|
|
| To UNSUBSCRIBE, just send mail to:
| basicstamps-unsubscribe@yahoogroups.com
| from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
|
|
| Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|
|
> I think what you need to do is what commercial telephone systems
do -- they
> give you a fake dialtone, you punch in the number, the system looks
for a
> long period with no keypresses, then checks the number and dials it
for you.
Hmmm - that would be the ideal. But I was trying to avoid the need
for buffering of out going numbers and fake dialtones
I'd prefer the pin to be entered first so that I dont incur
connection charges. It hadnt occured to me that *1234 would be
rejected by the exchange as "number not recognized" :-)
As long as *1234 is recognised by the exchange as invalid or benign
it would be OK. But I'd need to be careful there because certain
telecoms services such as divert use codes starting * or #.
What occurs to me is that if the first digit of a call is * then open
the relay (go onhook) until I have read and validated the PIN - then
close the relay again and then record but dont bar the call (assuming
the PIN was correct). That way the user would just hear a gap in
the dial tone while they enter the PIN. I'd have to provide some way
of providing the line voltage for this period to power the phones -
perhaps a choke or a 9v battery ??
>it would be OK. But I'd need to be careful there because certain
>telecoms services such as divert use codes starting * or #.
>What occurs to me is that if the first digit of a call is * then open
>the relay (go onhook) until I have read and validated the PIN - then
>close the relay again and then record but dont bar the call (assuming
>the PIN was correct). That way the user would just hear a gap in
>the dial tone while they enter the PIN. I'd have to provide some way
>of providing the line voltage for this period to power the phones -
>perhaps a choke or a 9v battery ??
How about (and I have just tried this on the BT network) using **1234 all I
got was "The service requested is not available" Assuming you have no
digital services set up on your line it should be fine. The line relay
could then drop and reinstate the line (so you get a new dial tone).
Justin