QoS for VOIP in my network

Hi guys,
I’ve a hybrid network I use Mikrotik Routers in the main NOC and Ubiquiti radios for the Wireless part, then I use unmanaged switches to each apartment and airRouter as Client Router, and then a VOIP ATA or VOIP Phone. Could you recommend me what is the best way to implement QoS to ensure good voice quality?

Thanks

Network diagram:

QOS is not a simple topic. At the high level you must mark everything that enters your network or have valid reason trust that it is marked correctly ( trust boundary and a trust relationship). Only marking VOIP will do practically nothing. The devices on your network must ALL support the type of QOS you choose to implement. An un-managed switch typically doesn’t do that. Cisco has some good videos on youtube. The hardware is different but the principals are the same.

Hi Zod,
What do you recommend DSCP or 802.1p for QoS?
Thanks,