What inexpensive equipment is used to "extend" a landline phone far, over IP?

Question

SIP

Good day!
Conditions: The house is connected to the Internet and one telephone line.
Task: In the cottage, which has recently extended the Internet to connect to the same telephone line, which is at Home.
Budget: up to 10k rub.
We need a pair of two voip devices, we will put one at home, the other in a cottage.
Everything is clear with voip adapters, they are as simple as 5 kopecks.
But with voip gateways, the questions are:
1) Can such a gateway act directly as a "sip-hoster", i.e. accept a connection from this very voip adapter, or do you need an intermediate sip server like asterix-a?
2) Is it possible to connect from a phone (android / ios) through the sip-clients built into them to this very voip-gateway?
3) Well, please advise a pair of pieces of iron
Thank you!

Answer 1

1) Yes, it can. Two sip-devices can communicate with each other without problems, without intermediate intermediaries.
2) Yes, you can. But the clients are not built-in, but free, available in the Market. These are CSipSimple and VoIP by AntiSIP. There are all sorts of others (Linphone), but these two are the most stable.
3) I can’t suggest SOHO hardware, I only worked with large office hardware.