How to set up so that connections do not fall asleep?

Question

network hardware

Dear experts, please tell me how to set up so that the connection through Mikrotik does not fall asleep?
The following situation Mikrotik is configured to work with Ats Agat UX with two providers, information in

topic

Setting up Microtik + SIP and SIP trunk, no voice coming through?

Now everything is working, but if calls do not go through the PBX to the provider that is connected via port 6 (WAN), after a while the connection with the provider stops working, as if the phone is connected, but the device itself does not work, neither incoming nor outgoing , but the SIP provider in your account thinks it is connected.
If everything is rebooted everything starts working.
If I ping from a computer, or Mikrotik, via IP, then outgoing through the PBX to the city do not fall off, but the incoming ones do not work. And if you make at least 1 call to the city, then incoming connections from the city rise.
If from a computer with a gateway 10.0.0.2, I ping the SIP domain RT 135595.14.rt.ru, I ping on IP 77.51.247.44, then I forcibly stop it and try to start it again, the computer tells me that it cannot detect the node 135595.14.rt.ru, and if I start to ping 77.51.247.44, then the IP address is pinged.
At the moment:
Established that for the incoming to work, you need a connection from each provider, circled in red. 1. In the PBX "Device functions" - "SIP" - tab "SIP Registrar" - "Maximum registration time (min)" changed the registration time to 3 minutes. 2. In Mikrotik in "IP" - "Firewall" - "Connections" there is a button "Tracking", there in "UDP Stream timeout:" the default value is 3 minutes.

Accordingly, after 3 minutes, Mikrotik breaks the connection, and the PBX is re-registered - the incoming connection via RT (which is in the internet) works.
But the SIP trunk connected to the MTS still does not work!
Of course, I set the day in "UDP Stream timeout:", now the day will not break, and what is the probability that the MTS SIP trunk will be outgoing in a day in order to start the day again, but I feel that this is not correct.
Now, with an incoming call to MTS on the ether5-MTS port, the whole trick is that the invite goes to 10.60.104.34 and this address should be essentially the PBX itself, since it is authorized by IP, and it is now the ether5-MTS port, and it is necessary that it be transferred to the automatic telephone exchange - 10.0.0.200. Here's how to do it, i xs (;

Answer 1

On automatic telephone exchange to include keepalive on trunks. Or re-register more often