VOIP call has no audio

Hardware MikroTik hardware general
1

I have Mikrotik router ccr 1036-12g-4s
and I have pbx Grandstream UCM6102 this pbx has sip trunking
the sip Registration is ok but No Audio on VoIP Calls

2

Is your grandstream behind NAT?
Have you done a trace to see where the grandstream is sending RTP packets?

3

Try to disable SIP in IP->Firewall->service ports (need restart router)
If not helping use packet sniffer and trace phone call … then analyze the traffic in Wireshark using tool telephony VoIP call …