How to connect a new number to the office?

Question

Mobile devices

Good afternoon. Another phone number is required for the office.
At the moment we have the following: In one room there is a router from Akado, 2 computers work in different rooms via direct connection via cable. In another one, where it is planned to connect the phone, the laptop from Wi-Fi works. Because the signal was not 100%, but somewhere around 50%, amplified with the help of another router - they set up a separate wifi client network.
As I understand it, we need IP telephony. The problem is that at the moment Router No. 2 is a simple D Link dir614 and most likely the phone will work from it.
What equipment is needed to connect the phone (1 number?) Will the network withstand, or does something need to be changed? A simple network map in the picture

Answer 1

You ask about the phone and you are asking for the local area.
So tell me what you want from telephone lines.
IP telephony in an office for four people is absolutely not profitable, at least on physical lines.
With analog lines PANASONIC KX-TEB308, three lines at the input, 8 inside

Answer 2

we have one city number (from MGTS). Due to the fact that part of the premises will be used for another direction, we need another city phone number.
Those with whom we cooperate said that we need to connect an IP phone, but they did not provide more specific information.
What we need: one additional landline number, one telephone set (you can even use an economy option), the possibility that when you call this number, a greeting would play: "You are welcomed by the Romashka company, blah blah blah ..." Later, in theory, we plan install another phone to which you could simply transfer the call. But it's later

Answer 3

1. Buy an IP phone.
I recommend wired - Yealink T19, T21. Inexpensive and very good. On Avito from 1000 rubles.
If you need a cordless handset (DECT) - Panasonic KX-TGP500B09. On Avito from 1500 rubles.
2. Remake the network as shown in the picture:
The router will do.
The cable between the two rooms must be thrown. Wi-Fi <--> Wi-Fi is always a bad idea.
3. Select a telephony provider, buy a number from them, enter SIP settings into the phone.
Settings figuratively speaking - server address, login, password.
I recommend the companies MCN, UIS, Zadarma, SIPUNI.