Telephony module (real phone line) for Pi?

I had another 'silent' call this morning, which reminded me that I'd
really like to screen incoming calls and handle known offenders (perhaps
in an offensive way). :-)
I Googled for telephony on the Pi but all I found were references to PABXs
for Internet Telephony.
Anyone know of a telephony module for the Pi?
I guess that a really old modem with voice capability might form a basis,
but modems are so last century.
So - anything in the pipeline or already there?
Cheers
Dave R
Reply to
David.WE.Roberts
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A USB softmodem might do the trick - see:
formatting link
aka
(looks like my idea to modify it to make an FXS port won't fly, though)
The rest of that thread has some other ideas too.
Theo
Reply to
Theo Markettos
there's linksys voip adaptors you could connect to the network socket.
OTOH a USB-POTS adaptor is basically a modem
--
?? 100% natural
Reply to
Jasen Betts
I don't know of anything you could plug directly into a phone line. The only FXO hardware for computers these days tends to be on a PCI card (I use an OpenVox A400); something like a PAP2T wants to do everything itself.
It's not too hard to get the CLID presentation off a modem, but actually handling a voice channel is a bit more of a challenge.
Reply to
Roger Bell_West
Why don't you switch to Internet Telephony? It is a lot more convenient to handle things like that in a PABX like Asterisk than to twiddle with phonelines.
So are analog phone lines...
I wrote software to do what you want for ZyXEL modems of the time, and it should work on a Pi when you have a serial port (via USB or via TTL->RS232 conversion) but as you wrote, it is all so last century...
Reply to
Rob
I would love to, but I use a BT service for that "Choose to refuse" as I get customers using Withheld or Unavailable numbers, that way the BT exchange blocks the call even if Withheld.
This is something you cannot do easily if anybody you need to speak with ever uses International, Withheld or Unavailable numbers.
To be pedantic even broadband routers have modems in them but for higher speeds than older dial up modems.
--
Paul Carpenter          | paul@pcserviceselectronics.co.uk 
    PC Services 
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Reply to
Paul
The Pi is just another Linux box - admittedly without PCI, etc. slots. So in that respect it's no different from running Asterisk (or Freeswitch) with an external ATA to do what you want.
It's been done - it's Linux. There are even some specialist versions of Raspbian for the Pi with asterisk which will do what you want. Just serch the raspberypi.org forums. Someone did it over a year ago. It's nothing special under Linux anymore.
Gordon
Reply to
Gordon Henderson
I know it is a PABX for internet telephony too, but what is wrong with asterisk?
I tried a conference, and the pi easily ran a sip conference with 40 participants.
Asterisk is easily scriptable, and you can have database access in the scripts.
-- mrr
Reply to
Morten Reistad
Analog phone lines are 19th century technology, the 20th century fixes are really just technology candy on top of a basic 19th century base.
It has been more than 60 years since the papers from bellcore that laid the ground for a digital phone system.
-- mrr
Reply to
Morten Reistad
If anyone manages to make that work I'd love to hear about it. I've tried and failed to get a couple of USB Winmodems to play with asterisk. Best I've managed so far is to get linux to see it, load the kernel modules etc but I can't get asterisk to talk to it at all.
(Admittedly not on a Pi, but it's all the same stuff really)
I'd love to get this working as I've got a 1957 strowger exchange in my front room which is currently hooked up to the internet via a PC with a 4 port FXO/FXS PCI card in it and I'd *love* to be able to replace that PC with a Pi and a bunch of USB modems all running off the exchange batteries.
I find it immensely irksome that the strowger kit consumes no power at all when idle (it only consumes power during a call) but the PC is sat there all the time humming away running up my leccy bill.
Rumour has it, you can make FXO/FXS ports out of sound cards, spit and string:
formatting link

I've never actually tried it though, as it looks a bit erm... nasty.
-Paul
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Reply to
LP
Thanks :-)
A sensible answer to the original question (some more further down as well).
It is quite a long time since I've seen an external modem which offers voice as well as data externally - could be as much as 30 years :-(
Just found this article

which points to

which is over £50.
As usual, double standards.
If I was connecting it to a £500 PC it might look reasonably priced.
More than the cost of a Pi though :-)
Cheers
Dave R
Reply to
David.WE.Roberts
I just leave an answering machine in circuit and turned on. At least the bastards will get billed for making the call even if they drop it without leaving a message.
However, a real solution needs legislation. Something along these lines would be good: if you're registered with the TPS and the call comes from a known offender, i.e. a number reported to the TPS or the ICO or a premium number then your telco should refuse to connect the number and should be entitled to recover the service's running costs by charging the caller. Note that its only the victim who is affected by withheld numbers. The telco certainly knows who made the call because they'll be billing them for it.
--
martin@   | Martin Gregorie 
gregorie. | Essex, UK 
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Reply to
Martin Gregorie
What sort of USB winmodems were you using? AFAICT getting winmodems to work at all in Linux is tricky (mainly because you need the whole DSP stack to do data and it's easier to just buy a hardmodem, so nobody wrote any drivers). And nobody uses modems any more so things have bitrotted (but then the hardware hasn't moved on either). I didn't manage to find (as in for sale) any winmodems that appeared as sound devices which Asterisk supports natively.
I do wonder how hard it can be to get audio in and out of a winmodem though - it's just a DAC/ADC on the end of a USB port. From what I saw in the slusb driver, most of the effort was on setting the sample rate than anything more complex. Possibly 5 minutes on a USB analyser would enable working out the protocol.
As another thought: are there any USB soundcards that use chipsets that provide the AMR riser normally found on motherboards? I suspect not, but an idea.
A fallback might be an RS232 voice modem - but I suspect this is going to be trickier to put into 'dumb DAC' mode. There might be more chance of it being documented, though.
Interesting. "Doesn't support ringing" is a bit of a showstopper. I imagine you could fake something up with a little transformer or a charge pump - it just might not ring a 1950s phone.
My objective was to find a winmodem that works as FXO without modification (so you can tell people to buy model X from ebay/Alibaba/etc) which I think the above will do (if I've successfully navigated the winmodem minefield), but providing ring current is going to mean something custom for FXS in any case.
Theo
Reply to
Theo Markettos
yeah, no ring or line voltage generator.
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?? 100% natural
Reply to
Jasen Betts
On 14 Jun 2013 20:42:12 +0100 (BST), Theo Markettos declaimed the following in comp.sys.raspberry-pi:
They are still useful for FAX work... And I'm afraid I still have a 20 hours/month "emergency" dial-up allotment on my Earthlink DSL service.
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	Wulfraed                 Dennis Lee Bieber         AF6VN 
        wlfraed@ix.netcom.com    HTTP://wlfraed.home.netcom.com/
Reply to
Dennis Lee Bieber
I got my Pi specifically to run an Asterisk based package called RASPBX and it is performing very well indeed.
Previously I ran a similar package called Trixbox on various desktop PCs and although that was also good it's very satisfying to do it on hardware powered by a spare Blackberry charger.
Incoming trunks and entire DDI ranges can be had for free, for most UK geographic STD codes, and outgoing calls can be made very cheaply on a PAYG basis eg less than 3p/min to call a UK mobile
Marketing calls can be discreetly transferred to a recording with strategic pauses that will keep the marketing agent in conversation for as long as it takes for them to "twig". Moreover, the system can record the result for my amusement.
RASPBX will do practically anything you could wish a PABX to do, eg. Interactive Voice Response menus of any degree of complexity you desire.
My favourite feature actually combines two features, Callback and DISA.
I dial a DDI on my mobile phone, the Pi received the call but does not answer the call, it effectively hangs up on me (so I incur no charge) The Pi now waits 5 seconds then calls back the number that has just called, I answer it and I now hear a PSTN style dial tone. I can now dial any number I like via the Pi either internally or externally.
This can be augmented so "family" mobile phones work as described above, but other CLIs will be asked to enter a PIN before they are played the dial tone.
The limiting factor of a system with comparatively limited processing power is the number of simultaneous calls that it can handle, as can limited upload broadband throughput, however, the Pi can cope with domestic usage and probably a lot of small business demands as well.
--
Graham. 

%Profound_observation%
Reply to
Graham.
True enough as it stands but the OP needs to interface a POTS line to a Pi running Asterix (or WHY) not VoIP provisioned "lines".
It's finding an "FXO Gateway" that doesn't cost more than a Pi that is the stumbling block. It might be simpler for the OP port his existing POTS number to a VoIP provider, whilst retaining the POTS line (with a new number) for delivery of internet and VoIP.
The problems that can come from this are BT ceasing the POTS line when the number is ported, the number change "breaking" the ADSL on the line. Running VoIP behind a NAT router (or on a dynamic IP) can be a "challenge" though I think Asterix is quite good at handling those situations. If it doesn't work you'll also need an ISP whose "customer support" have half a clue about IP address's, ports, filters, blocking, QOS etc...
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Cheers 
Dave.
Reply to
Dave Liquorice
Its not totally relevant, but a VOIP equipped router will give you usually two VOIP phone plus one 'the raw POTS LINE' sockets on the back iand is totally happy to route and prioritise calls using SIP, I know cos I has such (till the router died).
New CISCO 527 on the christmas list..
--
Ineptocracy 

(in-ep-toc?-ra-cy) ? a system of government where the least capable to lead are elected by the least capable of producing, and where the members of society least likely to sustain themselves or succeed, are rewarded with goods and services paid for by the confiscated wealth of a diminishing number of producers.
Reply to
The Natural Philosopher
Just for context I am a Virgin (ooo err Missus) Media cable customer. So I don't have ADSL on a POTS line.
I am reluctant to port the POTS number to a VOIP provider (although that is an interesting thought) because we don't use the land line much at all, apart from providing a non-Mobile number to show that we are genuine house owners and decent people and, of course, to receive Mumbai marketing calls.
We have had the same phone number for decades so it is also a port of call for long lost relatives etc.
Mainly I was looking at luxuries I could try out with the Pi - itself being a luxury.
One obvious thing was call screening - it would be nice to avoid interruptions during something important. The last silent call I was in the middle of cracking an egg which is something you can't easily just leave. [And no, that isn't code....]
We also have a '3' mobile with unlimited calls so that is used for virtually all outgoing calls apart from 0800 numbers (which I don't think VOIP makes free, although I could be wrong).
So - a nice project to play with incoming call handling on the Pi.
for £39.99 looks potentially the best option so far and about the same cost as a Pi.
Also I can play with it using some of the other computers.
However, I somehow expected there to be a board for the Pi to do telephony - but then again 'real' telephony using POTS is so last century so probably no interest these days. :-)
Anyway, the challenge is now to beat £39.99 for an FXO.
Cheers
Dave R
P.S. if we ported our current land line number to a VOIP provider does this mean we could re-direct calls to handsets/computers abroad, make calls from this number from abroad, and have a network based answering service?
It would be nice sometimes to appear at home when you are on holiday!
Reply to
David.WE.Roberts
I'd check that VM don't do silly things with ports, QOS, bandwidth control etc. But that's me I don't trust any of the big ISPs not to mess about with things.
I've just ported a couple of numbers to Sipgate, the outgoing CLI can be set to either the Sipgate number or the ported BT one via the web interface. Other providers are available and once the number is under their control can't see why it shouldn't be available for outgoing CLI.
B-)
Keeping the numbers is why I've ported.
So just ignore the phone if you are too busy to answer it or let an answering machine take it. They'll either leave a message or call back if it's important. Why do people have this compulsion to answer the phone
Not an option for us, mobile signals (all notworks) are too weak for reliable calls and the delay/quality of mobiles is awful.
Sipgate are free, you can sign up for free and make test calls to 0800 numbers without crediting the account. You can also call it. Again I think 0800 are free on most VoIP services, may even be a requirement as it could be very hard to tell if a "domestic phone" is a VoIP one or landline one.
Interest but getting approval for it without shoving the end price through the roof maybe a problem...
Probably I've not looked at that side very hard. But I know I can connect to my Sipgate account from anywhere on the internet (with enough bandwidth, a call to BT the other day ran at 100kbps each way) and make/receive calls. The outgoing CLI would be that set in the account. Think of the VoIP provider VoIP "instrument" link over the internet as a very long telephone extension cord. B-)
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Cheers 
Dave.
Reply to
Dave Liquorice

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