I need help with telephony. - Page 1
Forum section: electronics / general

author: Ampera
author_rank: Super Contributor
timestamp: September 03, 2016, 06:15:57 am
content: Strange title I am aware, but I have a few questions and have failed to figure out what I am exactly looking for, so maybe somebody here has some help.I am attempting to make a VoIP phone using a computer in order to tap into services like Google Voice that when registered in a proper country can make calls for free worldwide (Yet unconfirmed for me, but whatever, this isn't the issue.)I want the ability to somehow hook up a regular RJ11 phone handset like you would use for a Verizon/AT&T/T/Landline phone system for control on my computer. My first idea is to use a modem, but I got no clue where to start research for using it, and I don't know if a modem can directly control a phone handset. So my next idea is to use the 3.5mm audio jacks in order to control the phone using the sound card.I just don't know how I control the phone. From some research it appears an RJ11 jack for US landline phone has a ring/tip arrangement like a 3.5mm jack, and seems to just be a send/receive audio cable.However I don't know what impulses I need to send for things like Caller ID, Ringing the phone, and what to listen for for the reverse options.As to the question of why don't I use a USB phone or some other headset? I am designing it for the rest of my family with the intent they can use the exact same handsets they are using now, just without a phone bill. I am perfectly fine with forgoing a separate machine to begin with, and to just use personal rigs with regular headsets to make calls, but that isn't liked by everyone but me.So to sum up what I need, I want to know if it is possible to control a phone handset with a regular PCI modem, and if so how that is done/where do I find this info.Second if that is impossible, or as another idea, what impulses or tones does the US standard for Telephony use to do things like give Caller ID and to ring a phone forward and back.

author: joseph nicholas
author_rank: Frequent Contributor
timestamp: September 03, 2016, 07:28:00 am
content: There are dedicated Voip phones available to purchase cheaply on ebay, but I doubt thats the what you want. I´ve never seen the type of handset you describe with a phone plug. The R11 jack runs from the thing that generates the tones into the wall, the cable with the part you put to your head has a different size connector and won´t fit into the wall.I thing what you want to do with google won´t work because you wont deliver a ring signal the to alert the party you are calling. They would have to be sitting there holding the handset at the exact moment you call.

author: bingo600
author_rank: Super Contributor
timestamp: September 03, 2016, 08:01:55 am
content: You need an ATA (VoIP/Lan) to RJ11 "Box"Look for ie. the ones from Linksys SPA2102 (obsolete) , but i can't remember the name of the replacement.Look it up/Binfo

author: Halcyon
author_rank: Unknown
timestamp: September 03, 2016, 08:04:03 am
content: I would look at running something likeAsteriskon a low-power machine with some readily available VOIP phones (Asterisk promoteDigium IP phones.) From Asterisk you can then connect to various other services.My only other experience with using analog phones (connected to analog PABX line cards) was using Q-Master software, but that is more designed for call centres and NEC PABX systems.

author: edy
author_rank: Super Contributor
timestamp: September 03, 2016, 12:29:46 pm
content: Trying to run a full computer 24/7 just to keep an old phone running is a waste. You have several other easy options.One - subscribe to a cheap VOIP service like Vonage, Magic Jack or countless others. Free calls VOIP to VOIP and cheap to regular landlines. I believe they have family plans, you get several devices and send them to all your relatives. They also have apps and PC software. So you can manage your "family" or multi-location plan.Two - Get a cheap Android phone or tablet with no cellular service and have your relative link it up to their house WiFi. You should have a voice or video chat app installed on the smartphone. Easy to call them any time over the net.Trying to make one or all legacy telco-compatible phones in their house work with some PC based chat (like Google Voice, Skype or whatever) is a lot of work and more prone to problems and a waste of energy. A Full access point and Android phone, or a VOIP-dedicated box (like for Vonage, Magic Jack, etc) to plug in an old phone is much easier. Otherwise, if you still want a PC... you could get a Bluetooth headset and hack it to fit an old-Style phone. But you will still need a way to control the PC software to pick up, hang up calls, etc. As far as caller ID, you will be having a mix of calls (virtual and regular phone) so that is a whole other problem. What is the point of all this? The WiFi-linked tablet/phone with Skype or Google Voice type app makes the most sense.Just tell your relatives or buy a bunch of cheap Android phones, pre-install Skype or some other voice/video chat app and send it to them already set up with everybody's username already in the contact list. All they would need to do is join it to their WiFi. When family wants to call family for free, use the Android phone. We did that with BlackBerry Playbooks and our family is all connected for free whenever we want to chat.

author: helius
author_rank: Super Contributor
timestamp: September 03, 2016, 12:57:56 pm
content: A "full computer" is just a couple of watts these days. What you need is a telecom card with FXS ports, and software like Asterisk.You should be aware that the cards are business class products and priced accordingly.

author: Ampera
author_rank: Super Contributor
timestamp: September 03, 2016, 02:45:29 pm
content: Thanks for the alternative suggestions, but google voice is 100% free for whatever country you register it in. Everything else that is a service is not, but to clarify.How do I control from software a wireless plain jane handset with an RJ11 jack on itOr alternatively what signals go through the wire of an RJ11 cable to a phone in the US to control the phone like to ring and send caller ID.My alternatives are thoroughly explored and alternative VoIP services are exactly what we have now and exactly what we mean to replace.And computers can be made REALLY low power, and power consumption is not an issue for us. We have about 3-4 servers that can be running full storm at any time as well as serveral desktop computers.Either way this is actually a proof of concept for this and and option to us if we want to cut the cable and just use FiOS internet. TV might be easy, but not worth the money, but for now I want to see by using google voice's free US phone service and cheap/potentially free calls to another country like germany where family members live.

author: helius
author_rank: Super Contributor
timestamp: September 03, 2016, 05:17:12 pm
content: This is a handset:There is not much "controlling" involved. Audio goes in, audio comes out. The plug is certainly not a RJ-11.

author: Ampera
author_rank: Super Contributor
timestamp: September 03, 2016, 08:37:27 pm
content: By "Handset" I mean this. I apologize if people thought I was just talking about a simple in/out hand recivier.https://drive.google.com/open?id=0Bx-7TCgzh8ITSnJra25abDM3LVEhttps://drive.google.com/open?id=0Bx-7TCgzh8ITak9fVmVZWUNLNzAThis is what I want to control somehow using a Windows PC (Doesn't NEEEED to be windows, but that is where I am proof of concepting).I don't know if I could control it using audio ports on a sound card since the phone line IS an audio cable, or if I need a modem, but I want to know using either one how to ring the phone, give it CID data, make a tone run, and how to get calls and the like. I have been searching but haven't found something remotely relevant, so I am asking here hoping somebody can point me in the general direction I want to go.And at the end of each of those phones/handsets is a simple RJ11 phone jack.Thanks to the people trying to help. I know I haven't been too descriptive, but this is the same problem I am facing with searching. I don't know how to word it properly.

author: madires
author_rank: Super Contributor
timestamp: September 03, 2016, 08:51:35 pm
content: You need an VoIP ATA with a FXS port or a FXS card for the PC.

author: G7PSK
author_rank: Super Contributor
timestamp: September 03, 2016, 08:59:53 pm
content: Phone typically run on 48 to 50 volts with the ring signal a lot higher often around 90 or more I have seen 500 on some old hand cranked phones, I had one as a kid that I took the magneto out of to play with that produced enough power to knock you to the floor. I don't think it is feasible might be better to connect a mobile via blutooth.

author: Silveruser
author_rank: Regular Contributor
timestamp: September 03, 2016, 11:17:26 pm
content: You might want google POTS. Plain Old Telephone Service. As mentioned the normal line voltage is 48VDC with ring voltage around 100VAC at 20Hz or so. Then you have to deal with decoding the DTMF tones, generating dial tone etc. Caller ID is based on an old 1200 baud modem and sent after the second ring.Your basic audio card is of little use, you'll need something designed for a PBX or have fun reinventing a line card.

author: Ampera
author_rank: Super Contributor
timestamp: September 04, 2016, 01:50:06 am
content: Quote from: Silveruser on September 03, 2016, 11:17:26 pmThis is actually very helpful.So instead of a pattern, the phone just rings at a higher voltage.And after talking to somebody I am well aware now that an audio card would be totally useless.However I wonder if I can still use a sound card to send and give audio + commands to a custom board. Maybe even add in an RS232 signal, or just do something else.Either way this is very helpful, and I will try using POTS in my searches. Thank you.Also if anyone else has any other suggestions or advice, I would love to hear it.

author: Monkeh
author_rank: Super Contributor
timestamp: September 04, 2016, 01:53:55 am
content: What you are looking for is called an FXS.You want something like this:http://www.grandstream.com/products/gateways-and-atas/analog-voip-gateways/product/gxw4004/4008

author: Silveruser
author_rank: Regular Contributor
timestamp: September 04, 2016, 03:02:53 am
content: The ring is not just a higher voltage it is 20Hz AC. Keep in mind this is very old tech, even older than me! The first phones had real metal bells!

author: madires
author_rank: Super Contributor
timestamp: September 04, 2016, 10:06:14 am
content: The typcical ringing voltage here is about 50V AC (25Hz, PBXs also 50Hz). The allowed range is 32V up to 75V AC. Some PBXs/ATAs also support MWI via the line voltage method, i.e. 90V DC.

author: 1xrtt
author_rank: Regular Contributor
timestamp: September 04, 2016, 03:35:45 pm
content: As others said, you need an ATA (Analog Telephone Adapter) with a FXS port, to plug the analog phone.Doing a quick Google search, it seems that there is an ATA device specifc for connecting to Google Voice:https://www.obitalk.com/info/googlevoiceAnother option is to install Asterisk in an old computer (Even in a RPi) and integrate it with GV:https://wiki.asterisk.org/wiki/display/AST/Calling+using+Googlehttps://forums.anandtech.com/threads/asterisk-pbx-google-voice-how-i-set-up-100-free-landline-calling.2270051/That's give you more flexibility, as there are many ATA devices that interface with Asterisk, but also requires more configuration.

author: Ampera
author_rank: Super Contributor
timestamp: September 04, 2016, 05:40:21 pm
content: This is actually pretty neat. Thanks!