New old phone. Reinvent the PSTN phone

Now many say that switched PSTN is dying.
And the tendency to refuse wired phones, both among individuals and business users, confirms this fact - over the past years, the number of wired phones connected has been constantly falling.

Some users, mostly individuals, switch completely to GSM, some switch to virtual DID numbers using VOIP technologies (mainly business), etc.

This is a global trend.

But the problem is that the remaining users - all the same - a very large number in the world and it will remain large in the foreseeable future - 15-20 years for sure.
On the other hand, the growth of GSM users is also slowing down, their number is about the same in developed countries and they mostly migrate between mobile operators.

I would venture to suggest that both the growth of GSM and the drop in PSTN will eventually stabilize on some specific numbers and so will remain, i.e. both technologies will exist for a long time.

Let's take a look at the numbers in one of the most PSTN telephone countries in the world - the United States and see the FCC report published in February 2018 - exactly a year ago:





Let's take a look at the Retail Switched Access Line - these are the wired phones.

For 2016 in the USA there were 58 million of them, while GSM users had more than 340 million.
But in fact, 58 million is the number of PSTN lines in one household, but there may be several times more users — usually several people live in the house.

Therefore, if we are talking about PSTN users, albeit episodic, then 58 million can be multiplied by 3 and we will get a coverage figure of about 150 million, which is also not that small.

On the other hand, the number of VOIP telephony users is growing from year to year - the Interconnected VOIP Subscriptions string.

Now let's look at the users as a percentage:



Here is interesting the fact that users of wired PSTN among businesses more than among individuals - 40% and 35%, respectively.

Most likely this is due to the more conservative business users.

And surprisingly, OTT users of VOIP services (services like Vonage, etc.) are far more among physicists than in business - 47% versus 35%.

Let's look at the disadvantages of both pure PSTN connectivity and VOIP connectivity, which are offered by companies like Vonage.

Standard PSTN connection

1. The main drawback is the limited range of the home phone.

Cable limitation:



Limiting the range of DECT tubes - 100 meters:



2. Inconvenient phones with outdated design

Even if we take any new model of home DECT phone:



Using it now is the same as using the Nokia 3310 in 2019:



Even in the outdated Nokia functions will be more.

Disadvantages of OTT VOIP services (Vonage, etc.)

1. Not very convenient connection.

As a rule, VOIP services offer a pre-configured IP gateway with an FXS connection, which also proposes to include your regular desktop phone or DECT phone, with the same distance limitations.

Internet connection is also wired, i.e. You need to place this gateway near the router and next to the telephone line, which is not always convenient.



The main profit that the user receives is cheap intermountain / international calls.

2. Your existing, familiar wired number is not saved.

Although VOIP services claim that they can port your existing wired number to SIP, this is not always possible.

Even in the US, porting takes an average of 10 days and is also not always technically possible.
In other countries, the situation is even worse.

3. Disadvantages of SIP applications with DID numbers.

This applies to the service when you simply take DID numbers and use them in the SIP dialer on your smartphone.

The smartphone has a problem with pushing - for example, there are no iOS dialers that can push - as a result, you can call from such a SIP number on the iPhone, but the call is gone, the phone will fall asleep and will not wake up.

Although now there are VOIP providers that are pushing, but very few of them.
And again - as a rule, you will not be able to save your current physical line number.

On the other hand, in business, cloud or virtual PBX (WATS) is widely used, to which you can connect a gateway with FXO ports and save your old wired numbers.
Such cloud PBXs pass through the calls of users who are thousands of kilometers away and there is no loss in quality.

Also, very often on specialized forums, questions arise - how to forward a physical line using IP telephony to another location.

And in fact, for an ordinary user, the solution of such a seemingly rather simple question turns out to be difficult.

For this, it is usually advised to take a pair of gateways - one with FXO, the other with FXS and connect them through a SIP server.

Although gateways can work directly, by IP address, without a server, in practice this is done only when the devices are on the same LAN.

Those. in order to transfer a physical line to at least a SIP dialer in a smartphone, the user needs to buy a gateway with an FXO port, set it up, raise the server, set up routes, etc.

It is clear that an ordinary user can not do this, you need a specialist.

Because even setting up a simple gateway to an unprepared user can be quite difficult:



The idea was to make a cloud PBX, which would serve the single physical lines of ordinary users, replacing it with a completely stationary DECT base, and use the application on the user's smartphone as the end device.

And to do all this as simply and conveniently for the average user. Those. do something like a VATS for physical lines and private users.

As a device that connects directly to a wired PSTN line, a pre-configured gateway with FXO is used, but with a significant difference - this gateway with a Wi-Fi module.

All the user needs to do to set up is to connect it to his Wi-Fi network and turn on the telephone line.

It’s as simple as plugging in a smart outlet.

In addition, such a gateway can be installed instead of the DECT base of the phone, no need to make a wired connection to the router, which may be far from the telephone line.

Next, the user needs to put the application on your smartphone and ... everything.

Now all calls coming to the physical PSTN line are transferred to the application and the user can receive / make them from anywhere in the world where there is Internet.
As a result, you can save your home number, which is known to all friends and relatives (or office, which has long been known to customers) and at the same time use it in a new way, as a mobile number.

The cost of such a gateway is about $ 50, which is comparable to the cost of a DECT phone.
In comparison, for example, with GSM, there is no such thing as calls in roaming.

You can connect a large number of such FXO gateways to one application and receive calls from several lines (for example, both from the office and from home).

This solution has already been made and works as MVP, the application is for mobile OS - Android and iOS, and for desktops - Windows, Mac and Linux.

For mobile, the push mode works; In the standby mode, the application is turned off and does not consume anything from the battery of the smartphone.

Perhaps such a solution, if it turns out to be convenient for the average user and breathes new life into the PSTN.

The same is done for GSM, although the device is different - it is even simpler - a sim card is inserted, the user also needs only to configure the Wi-Fi and you can receive and make calls from this SIM card from the application, from anywhere in the world, ie . no roaming.

Crowdsharing equipment

Users of such gateways can give access to friends who know how to make outgoing calls through such PSTN or GSM lines.
Any user of the application with such access can make local city or mobile calls through such equipment.

I would like to hear the opinion of Habr's users on this project - whether such a solution is needed, is it worth adding some other functionality, etc.

Thanks in advance for the comments.

PS It turns out that telephone extension cables and long-range phones like Senao are still being sold.
In principle, it is a competitor to such solutions: