How to set up mikrotik for PBX Agat?

Question

Mikrotik

Situation. We have an IP-PBX AGAT CU-7212 with firmware version 1.0.1.119 and software version 3.5 (the last one that the manufacturer threw off). It is stuck in a Mikrotik, which leads to the gateway (also a Mikrotik). The Internet starts up properly, the devices are available. However, only internal communication works, it does not exist outside the office. PBX swears, they say, there is no connection to the server. I analyze traffic in wireshark - everything is in order and connections are established. The beeps go on, but the call is not made.