Post by thread:[EE]: Advice on learning how to design PBX systems

I've been frustrated by a lack of phone systems to suit my needs. Either they're too expensive (100+ port systems for thousands of dollars) or they're close, but not quite. The best thing I found seemed to be the BizFon (http://www.bizfon.com/), but after adding all the required options, I still didn't come up with what I wanted. So, I got to thinking: if I could build a box with a FireWire or USB port, then write software on my computer to drive it, I could come up with something great and easily extendible. I would like to build a hardware device that can connect to 8 or so POTS lines, and 8 analog phones. It needs to be able to handle incoming data like Caller ID data, and needs to be able to generate similar data (CallerID, message waiting indications, etc). for the phones connected to it. If there's a standard for digital phones, I'd like to try to support it, as well. It needs to be able to connect any CO port to any extension, and it needs to be able to digitize audio on any port, and output audio to any port. I plan to let the host computer handle the decision-making (recognizing DTMF tones, routing callers, etc.) and recording management (playing the right greetings, routing messages). And it needs to be able to handle a certain amount of simultaneous work. I know very, very little about how phones work. I have some notion that there are isolation needs to be met, and that voltages change to ring, etc. I know about A/D and D/A conversion. I know basic embedded development (I've done PIC work and SH2 work), although I'm not sure what processor I'd use for something like this, although I suspect something like a StrongARM or Embedded PowerPC is called for. I suspect that there are ICs for handling a lot of phone-related stuff, too. I'd appreciate advice and info about vendors of such chips, design ideas, literature, anything you think might help. Thank you very much. -- Rick -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Check out the links on http://www.epanorama.com/links/telephone.html There is some general info, though I couldn't find anything about a digital phone standard. Around where I live, the Nortel Meridian systems seem to be pretty widespread. Perhaps you can find some old phones at an auction or going out of business sale. Trying to figure out how they work might be a challenge. You could always buy some computers, distribute them around the house, and then do VoIP (Voice over IP). Josh -- A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. -Douglas Adams Rick Mann wrote: > So, I got to thinking: if I could build a box with a FireWire or USB port, > then write software on my computer to drive it, I could come up with > something great and easily extendible. > > I would like to build a hardware device that can connect to 8 or so POTS > lines, and 8 analog phones. It needs to be able to handle incoming data like > Caller ID data, and needs to be able to generate similar data (CallerID, > message waiting indications, etc). for the phones connected to it. If > there's a standard for digital phones, I'd like to try to support it, as > well. <Snip> > I know very, very little about how phones work. I have some notion that > there are isolation needs to be met, and that voltages change to ring, etc. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

On and off over the years I've though about this. The hardware is not difficult, the software glue that holds it together is what takes so long to implement. IF you want to build it from scratch, consider using modems as the phone line interface. You'll need to look around for the right modem. Some regular modems handle voice, caller ID, etc, but most sold now are 'winmodems' which are essentially sound cards hooked up to the phone line with some circuitry to detect ringing, pass CID signals, etc. There are linux drivers for these which might get you started on how to program for them. On the other end you'll want to essentially hook a sound card to a box that connects to the phone and has a ring generator and passes CID information. Radio Shack online has a box which connects a phone to the soundcard, you might look there for a simple schematic. Use relays to connect the phones to a ringer, and the CID signal is a simple 2400bps modem type signal (two tones) sent in between rings. At this point the software could simply shuttle the voice streams from one interface (modem) to the next (sound card) and back, or connect a relay between the two. If shuttling the sound then a voice mail system is not too much more work, and sending the signal over the LAN to the user's computer isn't very hard either. There is an open source voice over IP telephony solution which has a lot of this built in, but it may be overkill. Alternately you could have a bank of ring detectors, touch tone decoders, and CID readers on the line side with a bank of relays connecting phones to the various incoming lines. The phone side would have a ring generator, touch tone decoder, and CID generator. This assembly could be controlled by a pic with a 115.2kbps connection to a computer. This should be fast enough for all the data that needs to be transferred. Attach a few sound cards to the system (which can be switched to either the lines or the phones as needed) to give voice prompts and voice mail. It might be worthwhile, however, for you to look into voice over ip solutions. CISCO sells a nifty unit that turns any regular phone into an IP phone. -Adam Rick Mann wrote: {Quote hidden}>I've been frustrated by a lack of phone systems to suit my needs. Either >they're too expensive (100+ port systems for thousands of dollars) or >they're close, but not quite. The best thing I found seemed to be the BizFon >(http://www.bizfon.com/), but after adding all the required options, I still >didn't come up with what I wanted. > >So, I got to thinking: if I could build a box with a FireWire or USB port, >then write software on my computer to drive it, I could come up with >something great and easily extendible. > >I would like to build a hardware device that can connect to 8 or so POTS >lines, and 8 analog phones. It needs to be able to handle incoming data like >Caller ID data, and needs to be able to generate similar data (CallerID, >message waiting indications, etc). for the phones connected to it. If >there's a standard for digital phones, I'd like to try to support it, as >well. > >It needs to be able to connect any CO port to any extension, and it needs to >be able to digitize audio on any port, and output audio to any port. I plan >to let the host computer handle the decision-making (recognizing DTMF tones, >routing callers, etc.) and recording management (playing the right >greetings, routing messages). And it needs to be able to handle a certain >amount of simultaneous work. > >I know very, very little about how phones work. I have some notion that >there are isolation needs to be met, and that voltages change to ring, etc. >I know about A/D and D/A conversion. I know basic embedded development (I've >done PIC work and SH2 work), although I'm not sure what processor I'd use >for something like this, although I suspect something like a StrongARM or >Embedded PowerPC is called for. > >I suspect that there are ICs for handling a lot of phone-related stuff, too. > >I'd appreciate advice and info about vendors of such chips, design ideas, >literature, anything you think might help. Thank you very much. > > >-- >Rick > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body > > > > > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

Try google on 'pc pbx' and 'linux pbx' Chris On Wed, 2002-07-24 at 21:10, Rick Mann wrote: {Quote hidden}> I've been frustrated by a lack of phone systems to suit my needs. Either > they're too expensive (100+ port systems for thousands of dollars) or > they're close, but not quite. The best thing I found seemed to be the BizFon > (http://www.bizfon.com/), but after adding all the required options, I still > didn't come up with what I wanted. > > So, I got to thinking: if I could build a box with a FireWire or USB port, > then write software on my computer to drive it, I could come up with > something great and easily extendible. > > I would like to build a hardware device that can connect to 8 or so POTS > lines, and 8 analog phones. It needs to be able to handle incoming data like > Caller ID data, and needs to be able to generate similar data (CallerID, > message waiting indications, etc). for the phones connected to it. If > there's a standard for digital phones, I'd like to try to support it, as > well. > > It needs to be able to connect any CO port to any extension, and it needs to > be able to digitize audio on any port, and output audio to any port. I plan > to let the host computer handle the decision-making (recognizing DTMF tones, > routing callers, etc.) and recording management (playing the right > greetings, routing messages). And it needs to be able to handle a certain > amount of simultaneous work. > > I know very, very little about how phones work. I have some notion that > there are isolation needs to be met, and that voltages change to ring, etc. > I know about A/D and D/A conversion. I know basic embedded development (I've > done PIC work and SH2 work), although I'm not sure what processor I'd use > for something like this, although I suspect something like a StrongARM or > Embedded PowerPC is called for. > > I suspect that there are ICs for handling a lot of phone-related stuff, too. > > I'd appreciate advice and info about vendors of such chips, design ideas, > literature, anything you think might help. Thank you very much. > > > -- > Rick > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Rick, Building a PBX is fairly simple, if you have the right hardware and software at your disposal. The problem is that the software and hardware are not cheap. For the hardware and software, I always use Dialogic (but there are cheaper sources). A D41/ESC card will support 4 analogue lines. Youcan have upto 8 cards in one system. Or, if you prefere, you can fit D300 cards that will accept an E1 (30xISDN) Again, you can have upto 8 cards in a system. There are variations on these cards for USA (T1) support. The software is usually sold on a per/channel basis. Parity software, now part of Dialogic, that is now all owned by Intel, do a product called VOS. You can throw together a complete system in a matter of hours (if you know the language). I've built complete systems, integrating with MS SQL Server and doing all sorts of strange things in a matter of days. Check out www.intel.com/network/csp/trans/dialogic.htm Voice Mail, FAX support, SMS support, FTP, WEB etc etc are all available. The advantage of using, for example D41/D300 cards is that DTMF, CLI etc is all built in. Also, the boards have DSP for audio prompt play back (at different qualities), speech recognition, voice capture and a whole host of other features. All on a half or full size ISA/PCI card. Also, remember that there is legislation about what you can connect to the phone network. You might want to look into using TAPI. There are some TAPI boxs around that might do what you want. Also, TAPI is supported under Windows 2000 so you could write the software in Visual Basic or C++. On Wed, 2002-07-24 at 21:10, Rick Mann wrote: {Quote hidden}> I've been frustrated by a lack of phone systems to suit my needs. Either > they're too expensive (100+ port systems for thousands of dollars) or > they're close, but not quite. The best thing I found seemed to be the BizFon > (http://www.bizfon.com/), but after adding all the required options, I still > didn't come up with what I wanted. > > So, I got to thinking: if I could build a box with a FireWire or USB port, > then write software on my computer to drive it, I could come up with > something great and easily extendible. > > I would like to build a hardware device that can connect to 8 or so POTS > lines, and 8 analog phones. It needs to be able to handle incoming data like > Caller ID data, and needs to be able to generate similar data (CallerID, > message waiting indications, etc). for the phones connected to it. If > there's a standard for digital phones, I'd like to try to support it, as > well. > > It needs to be able to connect any CO port to any extension, and it needs to > be able to digitize audio on any port, and output audio to any port. I plan > to let the host computer handle the decision-making (recognizing DTMF tones, > routing callers, etc.) and recording management (playing the right > greetings, routing messages). And it needs to be able to handle a certain > amount of simultaneous work. > > I know very, very little about how phones work. I have some notion that > there are isolation needs to be met, and that voltages change to ring, etc. > I know about A/D and D/A conversion. I know basic embedded development (I've > done PIC work and SH2 work), although I'm not sure what processor I'd use > for something like this, although I suspect something like a StrongARM or > Embedded PowerPC is called for. > > I suspect that there are ICs for handling a lot of phone-related stuff, too. > > I'd appreciate advice and info about vendors of such chips, design ideas, > literature, anything you think might help. Thank you very much. > > > -- > Rick > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads