Elastix in the cloud with its own IP. Can't hear the other party when making a call?

Question

Elastix

The situation is this. There is Elastix 4 on the cloud with its own dedicated IP address. There are several offices. Almost everywhere everything functions perfectly, the call goes through, the voice is heard both of the caller and the one who was called. But there is a problem in one of the offices. The beep goes on, but no voice is heard. The employee who calls does not hear the one who called (beep, there is a ringtone, you can hear), but the one who called hears everything. There is Mikrotik in the office (but the same Mikrotik is in another, with the same NAT settings and Firewall). Maybe there is something in Mikrotike itself that does not miss a voice or something else?