Internet Telephone

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Does a simple Internet telephone interface exist?

I think perhaps not, or not at a cost less than $200.

Google finds plenty of devices, but most have complexities I just don't  

Let me explain and specify what I'd like.

I'd like a device, probably not much bigger than a USB memory stick, which  
has just three connectors. Power, RJ11 and RJ45. A POE option might also be  
useful which would leave the power connector unused.

RJ11 connects to a standard telephone.

RJ45 connects to the Internet, either directly to a modem or through a NAT  

Using two of these devices, with each device at a different location, I can  
talk to someone, just like a telephone call, who has their device connected  
to a standard telephone and also to the Internet.

The device will get its IP address using DHCP and perhaps light up a green  
LED when it's successfully obtained an IP address.

When I make a phone call I make it to a remote IP address not a phone  

The destination IP address has another identical device connected to the  
Internet and to a standard telephone.

To keep it simple, the device is configured via the telephone keypad and  
might reply with one beep when a command is understood and actioned or with  
two beeps for WTF do you mean?

I might use a key sequence like ###123#124#125#126##200* which means make an  
outbound TCP/IP connection to a remote device where the remote device is at and is listening on port 200. Another green LED might light  
up when the TCP/IP Internet connection is successfully established between  
two devices.

The remote destination device might be configured with a key sequence such  
as ##200* which means listen for an inbound connection to port 200. If the  
device is behind NAT then a port will also have to be forwarded in the NAT  

Other key sequences might be provided for lesser used configurations such as  
static IP and lockout of further configuration until reset.

Whether the configuration is retained without power depends on cost.

No complicated http configuration interface is wanted or needed but a  
recessed reset button would be useful to wipe all existing configuration.

Encryption is not required. If you want encryption then make a VPN between  
two routers.

Another useful feature might be the ability to connect one of the devices to  
a phone line rather than a telephone. Then my home phone can be used  
anywhere in the world if my remote device can establish a TCP/IP connection  
to my home device.

I've been doing a lot of Googling on this and found the Tiger560B but I want  
a device directly online, not via a computer with all the software  
complexities that requires. Keep the software to 8051 complexity level if  
possible then I can maybe write it myself. Google found other chips which  
could perhaps be used together to almost complete the picture. The WIZnet  
W7100A is nice but the serial interface, if it's fast enough, isn't going to  
be directly compatible with the MC14LC5480 which might then connect to a  
CPC5622. Perhaps the serial interface translation, a DTMF decoder, a  
configuration reply beep generator, and any remaining glue logic can be put  
in a custom chip.

There are likely to be many things I haven't thought of. Some of which might  
mean it isn't feasible. One possible problem is how do you know a call is  
coming in? Is it feasible for the device to be able to make the connected  
phone ring? Something tells me that this might require a transformer which  
makes the device a bit bigger but perhaps not too big.

Re: Internet Telephone
On Tue, 16 Aug 2016 15:44:30 -0400, John Smith wrote:

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If you're eskert of anything too complicated to run on an 8051 then you  
may as well lay down the project now.

You don't need a transformer to make a phone ring.  For most electronic  
phones you can just drive an interrupted 24V to the phone and get it to  
ring, but for an old electro-mechanical ringer you really need that good  
old 100V RMS 20Hz business.

I think it's quite doable, even with the ringing, but not unless you're  
happy with playing with TCP/IP stacks and other Ethernet fun stuff.

Tim Wescott
Control systems, embedded software and circuit design
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Re: Internet Telephone
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Ok. Let's say my phone line interface uses a CPC5622.
To get 24V the device will either have to be powered from 24V or convert a  
lower voltage rail up to a suitable 24V. There may be further complications  
if I want it to be connectable to a phone line as well as a phone.

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I'm happy playing with TCP/IP but I'm not likely to code a TCP/IP stack  
To have any chance of doing it myself I'd have to use the WIZnet W7100A.

Thanks for your reply.

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Re: Internet Telephone
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I think it might be cleaner to use an isolated ringing circuit such as the  
transformer coupled one on this page.
I think it would have to be disconnected with a relay when the phone picks  
The complete device could then be powered from 12V DC with a switcher for  
whatever the chips need.

If I want to make further progress I think the CPC5622 evaluation board is  

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Re: Internet Telephone
MagicJack.  Ok, so it's USB, but you could insert an MCU with USB and  
Ethernet inbetween, assuming you can get all the drivers and usage rights to  
do it this way (maybe talk to MJ themselves about realizing the full  

Putting all the interface at the handset side seems rather ambitious, but it  
would be easy enough (relatively speaking) to put a voice interface in  
there.  "Press 1 to configure your D.H.C.P. settings, press.."  Or, ehh...  

Or it already exists and I simply don't know, because I don't shop around  
for this kind of thing. :P


Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
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Re: Internet Telephone
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Yes I found them on my Google travels.
If it has to have a USB bridge then Tiger560B is also an option.

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Google hasn't found anything close to my exact requirement although there  
may be some very expensive boxes which can do that and a lot of other  
This surprised me a little but maybe it's because although the average  
person is familiar with phone numbers, doing things by IP address is another  
matter, and few people have a static IPV4 address.

Thanks for your reply.

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Re: Internet Telephone
On 8/16/2016 6:39 PM, John Smith wrote:
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Something like a MJ has the hardware, but the software normally works  
through a provider which connects you to the POTS network.  You would  
need to rewrite the software to make it work directly to another unit as  
you describe.

I have a Nettalk DUO which I paid $50 for including a year of service.  
Now I see they are $15 with three months service.  It would have all the  
electronics you would need, but contains a ARM most likely that you  
would need to program your way.  RJ-45, RJ-11 and USB for power.

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I'm not sure how well a direct IP connection would work.  Otherwise  
people would be doing it.  I seem to recall reading that some services  
support direct IP to IP connection... but it's still through them.  Do  
you understand the protocols enough to figure it all out?


Rick C

Re: Internet Telephone
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There are two problems with it:

1. it requires that the phone is on an address reachable from the caller,
   so not behind a NAT router.  LAN or VPN is fine.

2. when the phone is exposed to the world (internet), it will receive
   so many phantom calls that it is not fun to use.

Re: Internet Telephone
On 8/19/2016 7:56 AM, Rob wrote:
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It is, also, completely unregulated/protected.

I.e., no "wire tap" laws, rights to privacy, quality of service
(as well as "availability") guarantees, etc.

(But, then again, much of that is true for cell phones, as well!)

OTOH, you could always layer other protocols on top that can
fix most of these problems and actually provide a *better* service
than a land line -- but, you'd have to enlist the cooperation of
others (including everyone with whom you want to speak)

Re: Internet Telephone
On 8/19/2016 10:56 AM, Rob wrote:
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That's not hard to deal with by requiring a passcode of some sort.


Rick C

Re: Internet Telephone
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The usual solution is to delegate that kind of validation to a separate
server.  The phone is configured to subscribe to a certain phone number
using credentials (password), at some server (PBX).  When making a call,
the server receives the called number, checks how it can reach that
(also subscribed number, or reachable via some other exchange that it has
a trunk connection to), and then forwards the call.

The advantage is that the caller does not have to know the IP address
of the destination, but only the telephone number.  It works much like
the existing POTS system, so it is familiar to the users.

The main difference is that the exchange is no longer an expensive piece
of equipment that only a phone corporation can install and maintain, but
it can be any small computer system including a Raspberry Pi.

So you can build your own small telephone network this way, independently
from the phone company (but of course dependent on the internet).

My phone can make 4 such connections, I have two that each are to a
provider that also allows connection to POTS numbers (using some gateway),
and one that is a Raspberry Pi shared with friends.  So no need to make
direct IP to IP calls.

Re: Internet Telephone
Here you go.  Duo to Duo free comms.

Don't know if you still need to pay for an annual plan.  Nettalk is one  
of those companies that are very stingy with info.


Rick C

Re: Internet Telephone
On Tue, 16 Aug 2016 16:55:12 -0500 "Tim Williams"

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Don't bother, It's practically worthless IME. Dropped calls, calls that
never make it through, and useless support.

Re: Internet Telephone
On 8/17/2016 5:24 AM, JW wrote:
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Lots of people have trouble with their service, but I don't know how  
much of that is the service and how much is their Internet connection.  
I couldn't use my Nettalk DUO very well, but that's because of my  
Internet connection.


Rick C

Re: Internet Telephone
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This is not odd, this is how every IP network works when it is nearly
saturated.  IP was not designed with realtime specification.

QoS tries to work around that by using different relative priorities
for packets, but that is also the reason why many ISPs don't want to
implement it in their networks: as soon as the bad people find out
that they can get an advantage by tagging their packets with a suitable
QoS value (not only their voice traffic, but all of their traffic), they
will do so and will make the network perform even worse for those that
do not have this knowledge.

Re: Internet Telephone
On Tuesday, August 16, 2016 at 12:43:19 PM UTC-7, John Smith wrote:
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Vonage, maybe?

There's even a mobile phone app for Vonage that allows you to place a call while using wifi through your mobile phone.  It came in really useful when placing calls to the US cheaply while I was vacationing in Asia.


Re: Internet Telephone wrote:
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    Magic Jack also has an app for that. I use it on a tablet, and on a  
used HTC EVO 4G phone with no phone service. I spent $6 for it, on Ebay.  
  I have had the Magic Jack Plus for several years, It has a USB or  
network interface and is powered from its USB port. The sound quality is  
good. I talk from Florida to California quite often and I have had no  
problem with it, unlike the early USB only version. A five year prepay  
was $100, when I renewed the account in 2013.

Re: Internet Telephone
On 8/24/2016 2:40 PM, Michael A. Terrell wrote:
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So you can buy an old smart phone cheaply and just use the wifi  
capability?  I might give that a try.  Cells don't work well here.  This  
would be through Magic Jack?  How do I tell if my Internet connection  
will support VOIP?  I'm pretty sure it isn't good enough for that, but  
I'm willing to try it.  Hmm... do the have an app for a PC?  A set of  
headphones would suit me ok, especially if they are bluetooth.


Rick C

Re: Internet Telephone
On 24/08/2016 19:59, rickman wrote:
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Only if you are not paying for the internet data connection.
(depending where you are mobile data prices can be usurious)

Quite a few mobile carriers offer an app that will route calls over Wifi  
when it is available either as an optional extra or automatically.

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Cell phone with an external antenna connection pointed at the nearest  
base station (provided it is less than 35km way?). I use this method for  
a fast internet connection when my wired ADSL cannot cope.

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Quick test is download an internet radio program or Skype (yuk).

It would have to be dire internet not to support VOIP (or deliberately  
hobbled by your ISP to delay or drop VOIP packets - whatever happened to  
net neutrality?). You only require around 128kbps channel capacity for  
near broadcast quality sound with a decent encoder. Speech is  
intelligible with a much lower bandwidth if you don't mind cheats.

Martin Brown

Re: Internet Telephone
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It is not as simple as that.  Customers want "bitrate" and measure
their internet connection using speed check tools that perform big
downloads and uploads.  To optimize the numbers returned from those
tests, internet providers and equipment manufacturers increase the
size of buffers in network equipment ("buffer bloat").

This optimizes the speed of large transfers, but it interferes with
the "real time" capabilities of the system (that were never designed
in, but it sort of worked unless you loaded the connection to the max).

Now, when you send your voice packet that you expect to arrive in
20ms, it has to queue behind a long list of packets belonging to a
file download, being buffered to optimize that download.

It is not the same at every ISP, and the ISP can do something about
it e.g. by configuring "fair queuing" on their customer-facing routers,
or even implement QoS (= allow the VoIP packets to specify that they
want to be at the head of the queue, rather than at the tail, using
an IP header field called DSCP).

Some ISPs don't want to invest time (= money) into optimizing their
equipment for VoIP, but I would not want to call the "hobbled by the
ISP".  It is more work for them, and they don't get more money for it.
Also, implementing QoS opens a door to abuse.  When the bad guys notice
it, it may be they will foul up the system by tagging all their bulk
traffic as high priority.

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