hpr-knowledge-base/hpr_transcripts/hpr4441.txt

Episode: 4441
Title: HPR4441: Voice Over IP
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr4441/hpr4441.mp3
Transcribed: 2025-10-26 00:44:23

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This is Hacker Public Radio Episode 4441 from Monday 11th of August 2025.
Today's show is entitled Voice Over IP.
It is the 20th show of Lee and is about 11 minutes long.
It carries a clean flag.
The summary is, Lee talks about using a voice over IP telephone.
Hello, I'm Lee.
I'm going to talk today about setting up a voice over IP phone.
So when you're talking about a landline phone, this traditionally worked over the play
no telephone system or POTS pops and it would work by transmitting audio frequencies
as analog signals and downcon for wires.
The routing of course would occur at the exchange that interpreted what was originally
a series of clicks, but later a sequence of tones each consisting of two frequencies.
Typically, there'd be regional exchanges, then national and international exchanges to
route calls either locally or over long distances.
Now Voice Over IP is a digital means of communication, so data is transmitted in data packets
over a network.
These might be TCP or UDP packets and they're going across a network or in practice across
the global internet.
Now although there are numerous ways of transmitting by directional voice communications across
the internet nowadays, I'm only really talking about one of these when I refer to voice
over IP.
In some sense, things like Teams and WhatsApp and Google Me and the late but great Skype
all do this.
I'm using a strict definition.
The main protocol use for setting up the voice over IP calls I'm talking about is session
initiation, protocol OS, SIP, SIP.
Now phone and broadband providers, who might also provide television channels, at least
here in the United Kingdom, are all moving to make their phone services fully digital.
I'm not really going to delve in what they're doing, as to some extent whatever they provide
is completely transparent.
And by transparent, I'm in barely configurable, at least to the typical consumer.
So what I'm talking about is setting up your own generic voice over IP telephone, or
it could be a soft phone on the computer tablet mobile or in theory even LiOT device like
Smart TV or Smart Speaker for example.
I've got some experience with yelling phones and I hope that's how you pronounce it.
My current phone is label BT but I think it's just because it has been sold in a rebranded
form by that company.
So what do you need in addition to a voice over IP phone?
When theory and that you just love theory, in theory nothing else, since these phones
can just point to any IP address and talk to love a phone on that address.
In practice if it's not in some call centre you've set up and it's in your home or small
office, you don't want to be communicating with other phones by their IP address.
So you'll probably be wanting to phone real people using their real phone numbers outside
of your own network.
Now most like wearing networks or lands for short, I positioned off in their own IP address
range separate from the public internet.
Network address translation short and NIT or NAC typically provides the bridge between
what's on your LAN and what is on the wide area network, WAN or in other words the internet.
So your phone thankfully is not public because trust me if it was you'd get like a dozen
calls in a minute from the random bots that reside out there in the ether producing endless
noise in the form of spurious connections.
Although even with that some routers may be forwarding certain ports so you may get into
a little trouble with things connecting that shouldn't.
If that's the case you really need to check your router settings.
Of course the router can be important when it comes to quality of service and settings
like that that will help voice calls over voice over IP run more smoothly.
So to get over the bridge that's provided by NAC you'll probably be using a protocol
like session traversal utilities for that, abbreviated to stun STUN.
And in addition because you want to be talking to real telephones not just IP addresses you
want to be connecting to a server of voice over IP provider it can root calls onto the
real telephone networks of whatever countries you're calling.
In the past though set up VoIP phone for clients but currently for my own personal
use I use a provider called VoIP.MS.
It's got such and such regular amount for them providing you a real phone number and
a new pay for the calls you make.
To set up the phone you need the credentials from the VoIP provider like use the name password
and the server that the phone is connecting to.
My provider service all over I connect to the one in London, typically you'd connect
to the phone via its web interface from a browser running on a PC on the local network.
These admin interfaces are usually password collected, ideally when you log in the first
time you're tightened up this interface just so your internet connected toaster or whatever
sitting on your land doesn't get it in its head to log in as admin strike admin and start
messing with things.
One of the things about VoIP to be aware of is that in principle there's no difference
between a local or national or an international call.
One thing to get used to is you'll probably always need to include the international
dialing code prefix in any number you're dialing.
When I set the service up I did have to enable which countries I wanted to be able to connect
to, but calling someone down the road costs me the same, at least more or less, as calling
someone in another continent.
This can be a good or a bad thing.
I like my calls to appear local so I purchased a local number and display this as my outgoing
call righty starting 0203 and while London numbers are typically 0208 and 0207 the
0203 range was introduced fairly recently still with the need for more London based numbers.
Of course you'll get all kinds of scumbags purchasing or spoofing like call or national phone
numbers and calling you up asking you to provide your password for your internet banking
and such and such.
So be aware sometimes your voiceover IP calls might be met with suspicion based on various
factors.
If like me most of the people you call already know your number in their contact list this
is not so much a problem.
Now set up my number a couple of years ago.
What I learnt first hand was that the rooting for these calls is not to be taken for granted
as for normal phone calls.
The voiceover IP provider seemed to need to do quite a bit behind the scenes to get calls
rooted to the right place.
This may have been more pronounced for me since my provider was American and I'm in the
UK so I had to train the dragon meaning every time I called someone new and the call did
not get rooted I'd have to lock the issue of the provider for them to sort out the rooting.
Eventually after enough training I was seamlessly getting through to 90% of the people I called
and to be honest now I don't even recall the last time a call got stuck at the rooting
stage.
Being interesting I just came across with voiceover IP phones that I was vaguely aware before
is you can register your number with emergency services so if you call 911 or 999 whatever
while your house is burning down they can immediately be dispatching a fire truck even
before you've told them your address.
How does voiceover IP compare with the mobile and traditional landlines?
I guess in terms of audio quality I don't notice the difference but then I'm not that
fussy about that sort of thing.
In terms of availability of operation, voice phones suffer a small inconvenience in that
they need both power and stable internet connection.
Mobile's work on battery, traditional landlines could potentially operate even in absence
of power since their low power and enough juice comes over the copper wires.
Now with the switch to voiceover digital, at least here in the UK you'll find there
is not much chance of making landline calls if there's a power cut.
And since most people have a mobile spare that's not such a concern.
What do I like about the voiceover IP phone I set up?
Well this only happened recently when I moved to a different flat with a different broadband
provider and all I had to do was plug my voiceover IP telephone into the broadband with an
ethernet cable and I behold it was immediately working, is in the same number as before,
without having to notify anyone of anything, do any kind of porting and trust me I've been
through porting hell at some points in the past with respect to work and that was when
my client was moving from ISDN if you remember what that was to voiceover IP.
What do I not like?
I guess the main downside is cost, the flexibility comes at a certain price.
That's not to say it can't be more economical than the alternatives in some circumstances
depending on the intended and actual usage.
Another aspect of voiceover IP I touched on before is it does not necessarily need a physical
telephone, it can operate on a computer or other device.
I've been successfully making calls on my mobile devices with an app called GroundWire and
on my PC with a Linux application called Linfone.
By the way I wish Linfone would introduce a dark mode because it has a theme that is
very much orange and gray on glaring white backgrounds.
When I mention these soft phones, these are operating exactly like the physical handset,
so have the same phone number and call or idea and so on, except they're running on lap
or in software, so the sound is through your headphones or PC speaker and mic or your
mobile or tablet speaker and mic.
So there's some nice things about voiceover IP I haven't gone into.
There's a whole playground of options around automated call handling, menus, call recording,
voice mail, redirecting calls to your mobile and vice versa.
Some of these might cost extra depending on the voiceover IP provider, and I've not
really used these services, so I can't describe in detail, other than to know that since
the telephony is to find it entirely within software and standard protocols, things become
very flexible, especially in terms of what you can do yourself without necessarily paying
or relying on third parties to do these things for you, but the exception of your VoIP
provider compared to what you might have been used to with traditional landlines.
I'm aware there are systems for setting up a whole fleet or at least maybe a medium-sized
office of voiceover IP phones, like asterisk for example, and this can do lots of professional
level stuff but I've never used it in practice, so I can't really go into it other than to
say this sort of system is probably what you might be using if you had a reasonably sized
business, and we're setting up your own voiceover IP.
Anyway, this has been rather short introduction into the Inquites proper voiceover IP, where
it's not something that's necessarily provided for you, but something you just buy the equipment
or download whatever software, it's up in account with a VoIP service provider that uses
open standards and then configure it to your heart's content.
If you know something more on this topic, want to record a show of your own?
Thanks for listening, bye.
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