How to connect 2 people at a distance of 50 meters for voice communication?

Question

Android

If 2 friends live in the same high-rise building, the distance between apartments is about 50 meters, how can you organize any type of communication for communication without delay (with a low latency), you can use voice (ip, sip, dect), you can somehow through local network (Internet operator one, there are static addresses, if it gives something)? I don’t understand much, but I would like to somehow organize a wireless local network or communication can be through 2 dect phones or a common wifi. The more budget option - the better, server, automatic telephone exchange, professional equipment for tens of thousands of dollars is not interested. Communication simply via the Internet due to weak routers, weak Internet (especially in the evening) and eternal overloads on the servers of instant messengers and clients is not suitable, plus the delay is very large.
Any articles with specific "recipes" for organizing such a connection are welcome.
Of the trash that can be used, there are two dect phones, each house has a router, there is one additional one, windows in the line of sight if you can build some kind of antennas.
The question is amateurish, sorry, 2 teenagers want to communicate as easily as possible without monthly payments (not counting the Internet at home), without buying supersystems, and without a 3-minute delay, so that they can play with all the fast emotions and chat and the sound quality was good, help me come up with )

Answer 1

order them walkie-talkies from Uncle Ali's cellars.
Now the sales are on.
and let enti teenagers crawl all over and subtract from the reports which walkie-talkies are best for them.
Well, walkie-talkies, if anything, in many cases you can apply.

Answer 2

Previously, such things were called "Walkie-Talkie"

Answer 3

DECT you yourself mentioned. There is often an intercom mode - a connection between the handset and the base (this is when the base has buttons and a speakerphone) or between two handsets tied to the same base. You turn on the intercom button, there is a call, at the other end they also press the intercom button - you can talk. All this does not require connection to a telephone line.

Answer 4

TeamSpeak , obviously.
Very old and still relevant program. There are no ready-made servers, you need to host it yourself somewhere. Well, that is, one of you must become a host for the server. Internet is not needed. Due to the fact that the program has been developed and maintained for a long time, there are very few bugs, so this is a reliable solution.

Answer 5

So if there is an Internet, what is the problem of calling on ANY messenger?

Answer 6

https://www.qrz.ru/schemes/contribute/icenet/IR/ir... they
promise up to 115200 baud, enough for voice

Answer 7

Install a Wi-fi bridge if you need a network with a normal speed, for example, such a NanoBeam 5AC-Gen2.

Answer 8

For communication at a distance of 50 meters, the choice of possibilities is huge.
1. Walkie-talkie. Recently I took Retevis radios to my nephews - 1300 rubles for a pair. Quietly covers a couple of hundred meters in dense urban areas. Of the minuses - half-duplex communication, lack of encryption (anyone can listen to the conversation and even participate in it)
2. DECT radiotelephones. On average, up to 300 meters in open space, 50 meters in a building. If there is a direct line of sight, it will work fine. It is better to install the base station on the windowsill. DECT support INTERCOM and several handsets.
3. If you have permanent IP addresses, you can use a direct SIP connection, calling a subscriber by IP (or IP:PORT), without any telephony servers like Asterisk.
Many SIP applications for PCs and smartphones can do this.
4. Wifi hotspot on the windowsill and application for communication within the network. The quality can be worse than DECT.
5. Flashlights and knowledge of Morse code :-)