How to setup PLAR on addpac ap-100b?

Question

Telephony

Good day to all. For the first time, addpac irons fell into my hand, and I got a little stupor.
There are two nodes.
192.168.0.90
192.168.0.91
The simplest analog phone is connected to each.
The task is worth the downtime utterly.
If you pick up the handset on the device that is connected to 192.168.0.90, immediately, without dialing the number, 192.168.0.91 should ring. And vice versa.
I read their documentation, forums, but there all the examples are too complicated. With automatic telephone exchanges, several networks, routes, and I have not yet been able to isolate the grain I need from there.
Judging by snippets of information from the forums, it seems like you can make a call without an internal number, directly to the ip address, and it even works, but I still could not figure out how to make this process automatic by picking up the phone.
Of course, I will continue to dig myself, but if anyone can share their experience, I would be very grateful.

PS. If you believe the forum www.xdsl.ru/svpro/viewtopic.php?f=4&t=5628&sid=aba... there is a similar setting somewhere even in the web interface, but either I'm blind, or there is none. Inside the menus, I revised everything 3 times, for something even remotely resembling a hotline