VoIP calls dropping. Disable SPI and SIP ALG?

Thank you for the answers!

Bandwidth: We have 50Mb down, 5Mb up. At most, we have 5 callers at the same time. We are currently using g.711 (ulaw) as the codec. Even with that codec (the least compressed), our bandwidth should be fine. I monitor everything with ‘The Dude’, and can see that there are no massive upload/downloads going on during the call drops.

CPU usage also does not appear to be a problem. It sits around 0% - 10%.

The only abnormal thing I have on the router is a HUGE static list of DNS entries for ad server blocking.

I have our phones set up to add the QOS fields on the ip packets, and a router mangle rule which counts them (and adds a ‘VoIP’ mark to them), so I know that the packets do indeed have QOS (DSCP TOS = 46) on them, and I think that is the best to use. I need to review that thouh.

Thanks for the help! Here is the printout of the two rules that ‘see’ the voip packets:

 2   ;;; voip tos 24
     chain=prerouting action=mark-packet new-packet-mark=VoIP passthrough=yes 
     dscp=46 

 3   ;;; VoIP RTP PORTS
     chain=prerouting action=mark-packet new-packet-mark=VoIP passthrough=no 
     protocol=udp port=10000-36000

Hmm… what I need is a VoIP guide for MikroTik. Any sources you’d recommend?