[Patentpractice] impossible to place international telephone calls? (was impossible to place a telephone call to China?)

[Carl Oppedahl]

On 6/17/2025 8:49 PM, Gerry Peters via Patentpractice wrote:
> I am very much open to advice from Carl or other VOIP nerds (and I use that term with the utmost respect) on the best workaround going forward...

It is interesting to think of different possible ways to conduct 
international telephone calls.

The general problem is the PSTN (public switched telephone network).  
The PSTN is the world we all knew thirty years ago. Thirty years ago, 
anybody who wanted to place any international telephone call would dial 
(for example) "011" and a country code and a city code and a telephone 
number, and the call would go through (or it would not, for any of a 
number of reasons).  But everything about the call completion path was 
determined by a single entity in the destination country.  That single 
entity was typically the post office in that country or it was a single 
private company that was not at arm's length from the government in that 
country.

It was simple (from the user point of view) and it was expensive.  And 
if a government wished to eavesdrop on phone calls, well, there was a 
way to do it across the board.  But was simple from the user point of view.

Now we are in the world of VOIP, which includes two interfaces. A first 
interface is DID world (direct inward dialing), meaning a way to obtain 
a (PSTN) telephone number almost anywhere in the world and to route 
inbound calls from the PSTN to one's own telephones or one's own PBX.  A 
second interface is A-Z service. This means a way to place an outbound 
call from one's own telephones or one's own PBX and the call will pass 
into the PSTN of any country starting with the countries that have a 
first letter "A" in their name and finishing with the countries that 
have a first letter "Z" in their name.  Hence the term "A-Z" service.

In plumbing we talk about a goesinna and a goesoutta.  For a water 
heater the "goesinna" is the place where cold water goes into the water 
heater, and the "goesoutta" is the place where hot water comes out of 
the water heater.  From the point of view of the human being who is 
trying to use the Internet as a way to connect with the PSTN, the DID is 
a "goesoutta" of the PSTN, a place where phone calls exit from the PSTN 
and pass into the internet, and once the calls reach the internet, the 
human being can control a lot about what happens to the phone calls.  
 From the point of view of that same human being who is trying to use 
the Internet as a way to connect with the PSTN, the A-Z service is a 
"goesinna" of the PSTN, a place where phone calls that originated on the 
internet pass into the PSTN, and once the calls pass into the PSTN, the 
human has little or no control about what happens to the phone calls.

 From the point of view of a government trying to control its phone 
calls in (the PSTN of) its country, the plumbing terminology reverses.  
 From the point of view of a government of a country, the "other" that 
the government seeks to control is VOIP.  So from the government's point 
of view, the DID is the "goesinna" namely the place where a telephone 
call exits the PSTN and passes /*into*/ the VOIP "cloud".  And from the 
government's point of view, the A-Z carrier is the "goesoutta" namely 
the place where a telephone call exits the VOIP cloud and passes 
/*into*/ the PSTN of that government's country.

Anyway, the DID world in a given country can be (and depending on the 
country, it is) a first choke point that the government may feel the 
need to control closely.  And the A-Z world in a given country can be 
(and depending on the country, it is) a second choke point that the 
government may likewise feel the need to control closely.

For a given company or individual that is trying to make use of VOIP, 
you might get your DIDs from any of a large number of DID service 
providers.  And you might get your A-Z service from a different service 
provider than the service providers from which you get your DIDs.  You 
might use several A-Z service providers, spreading out your outbound 
calls to one A-Z provider or another depending on the destination country.

Years ago my firm had DID numbers in several countries from several 
service providers and we got our A-Z service from just one of those same 
service providers.  But in more recent years my firm chose to simplify 
things and now we use a single service provider (VOIP.MS) for all of our 
DID needs and for all of our A-Z needs.

When I reported, a few days ago, that I was finding I could no longer 
place telephone calls to China, I was reporting an A-Z problem.

One of the fascinating aspects of VOIP service is to consider what 
happens if two parties who wish to call each other just happen to be 
getting their VOIP service from the same single service provider.  The 
extremely happy situation (from the point of view of those two parties) 
is that their call is able to start and finish without ever touching the 
PSTN.  It usually means the call is free of charge.  And it usually 
means the phone call goes through quickly and with a high quality 
connection.  And it often means the call is outside of the influence of 
any government (unless the service provider provides some back-door 
access to a government).

There is a patent firm in Poland that uses VOIP.MS (the same company 
that my firm uses).  I can call this patent firm on the phone and the 
call is free of charge and it is a high quality connection and the call 
goes through essentially instantly.  They can call me and it is the same 
happy situation.  Part of why things are so happy is that the call never 
touches the PSTN in the US or in Poland.

It is the same for a patent firm in the Netherlands.  They also use 
VOIP.MS.  Calls between their firm and ours are free of charge and the 
connection is high quality and the calls go through fast.

There are many countries around the world where there is a sort of 
similar situation for any two people who happen to be customers of the 
same mobile phone company.  In the US, for example, if a first Verizon 
mobile phone customer picks up their phone and dials the telephone 
number of a second Verizon mobile phone customer, the call will be free 
of charge and it will go through fast and it will be high quality.  The 
reason for this happy outcome is that the call bypasses the PSTN.  Same 
is true for a call where both customers use T-Mobile or both customers 
use AT&T mobile phone service.

A similar situation presents itself if two would-be communicators happen 
to both be Signal users.  If you use Signal to call me on Signal, then 
your call will bypass the PSTN and it will be free of charge and it 
might be high quality and might go through right away.   I have a Signal 
ID that is sort of like a telephone number.  If you are using Signal, 
you can call my Signal ID and your call will bypass the PSTN and it will 
be free of charge and it might be a pretty high quality telephone call.  
If you would like to try this, drop me a note and I will send you my 
Signal ID for an experiment.

Oh there is another fascinating aspect of all of this.  Suppose you are 
a VOIP user but your VOIP service provider is not VOIP.MS.  And suppose 
you want to place a telephone call to me (and I also use VOIP, in my 
case through VOIP.MS).  Is there a way to do this that also bypasses the 
PSTN?  The answer is yes.  There is such a thing as a "SIP URI".  For 
example you can "dial" a SIP URI that is "13032528800 at sip.oppedahl.com" 
and your call will pass from your VOIP service provider to my VOIP 
service provider in a way that bypasses the PSTN. No matter what country 
you are in, and no matter what country I am in, likely as not the call 
will cost very little (maybe free or maybe a penny per minute).  And the 
call might go through pretty fast and might be pretty high quality.

So where am I going with this in response to Gerry's question?

Part of where I am going with this is to invite people who might need to 
call each other to see if by any chance they happen to both be using the 
same VOIP service provider.  For example maybe they both use VOIP.MS.  
If so, then they can bypass the PSTN and they can make free calls to 
each other.  And the calls will go through fast and will probably be 
high quality.

A related concept would be to try to convince other parties to use the 
same VOIP service provider that you use.

Still another related concept is to start using Signal if you have not 
already done so.  If you are a Signal user, and if you have not already 
set up a Signal ID for yourself, then set up a Signal ID for yourself.  
And try to be alert to the possibility that some party that you would 
like to have a conversation with might also be a Signal user.  And you 
could give them your Signal ID.  Or they could give you their Signal 
ID.  Such phone calls will bypass the PSTN.

In your office or personal telephone system, you might want to set up 
one or more SIP URIs.  Share them with parties who might need to call 
you.  Send me a SIP URI and I can try calling you.

Another place that I am going with this is to invite people to learn 
about SIP URIs and to make use of them.  if you can figure out how to 
dial "13032528800 at sip.oppedahl.com" then you can call my law firm while 
bypassing the PSTN in your country and bypassing the PSTN in the United 
States.

Another thing to realize is that you should have been doing all of this 
four years ago.  See my blog article Shaking loose from the Public 
Switched Telephone Network (getting to know SIP URIs) 
<https://blog.oppedahl.com/shaking-loose-from-the-public-switched-telephone-network-getting-to-know-sip-uris/> 
which I published on August 31, 2020.

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