Good day!
I can properly configure QoS (Queues) for your SIP, because I am certified network engineer MTCTCE/MTCNA having over 10 years of experience in configuring, maintaining and troubleshooting of enterprise MikroTik devices.
Pay attention: if You don't use 100% your Internet channel, then QoS makes no sense.
Most likely the problem is in large delays between Your router and the SIP server (Asterisk).