How to turn 4 ordinary phone lines into something more

Question

Telephony

Given 1:
4 telephone lines, normal. Each is two wires plugged into ordinary telephones.
All 4 have one external number (multichannel). Not ip telephony. Although it may be somewhere there and ip, but we do not see it. The call comes to line number 1 and hammers into it until they answer, if line number 1 is busy, then it goes to number 2, with the same conditions.
I would like 1:
1-recording of conversations.
2- so that the call would walk along the lines with the condition "did not answer for 6 seconds OR the line is busy - transfer to the next line."
3- Ideally, let it all through the computer.

Given 2:
4 telephone lines, IP, connected through some Linksys iron, two lines per piece of iron. One multichannel external number. The call walks along the lines with the condition "did not answer for 6 seconds OR the line is busy - transfer to the next line." There is no password for iron settings.
I would like 2:
Connect all this with the telephone sets from “Given 1”, so that there would be not 8, but 4 telephone sets.

Which of these is really possible? What iron is needed, what servers / settings to raise, what manuals to smoke? Is the game worth the candle? A budget option is desirable, because the initiative is not corporate, but personal, for your own convenience.
There are no telephony skills yet, with the tag “not at all”.

Answer 1

Asterisk is here to help.

Answer 2

1) Negotiate with those who send calls.
2) Buy an analog gateway for 4 FXO and 4 FXS (meaningless).
3) Switch to IP telephony by ordering SIP to the same numbers from the provider.

Answer 3

Asterisk + 4FXO + customize this beauty.
But if there is a need not to at least do something out of this, namely, to receive calls with the indicated functions, it is easier to take a virtual PBX and not worry. You will pay 500 rubles a month.
An example right away is a virtual number on tekmi.ru . Immediately with the number, multi-channel, call recording, call forwarding, IP-telephony.

Answer 4

If you leave the old devices, then there is no point. It will be expensive with all the boards.
At least it's better to get rid of analog devices inside, the ideal option is also from the outside, as an option so as not to lay anything new, launch the adsl and get SIP through it. Well, commute it all through asterix.

Answer 5

there are a bunch of both one-port and many-port converters Fixed analog Phone Line <-> SIP. With a bang they are screwed to Asterisk'u at the level from the client to the two-way Peer'a.

Answer 6

Options:
1. install VoIP gateway and server with asterisk or 3CX