dealing with ridiculously low bandwidth and VOIP

Hi,

I've been trying to figure out the best way to deal with having a ridiculously low bandwidth and wanting to make phone calls.  The advice I could find in the knowledge base suggest using traffic shaping.  That turned out not to work, probably because it is impossible to control the incoming traffic.  With a downstream of only 455kbit/s, all the available bandwidth is always more than occupied unless nothing else goes over the line, or I limit the bandwidth usage of the applications receiving traffic from the internet --- which gets annoying.

Finally I found some time to experiment with this and seem to have found a solution: limit the incoming traffic with a fixed limiter instead of trying to shape the traffic depending on demand.  The configuration for this currently looks like this:

ubnt@ubnt# show traffic-policy 
 fair-queue fair {
     hash-interval 5
     queue-limit 20
 }
 limiter lim1 {
     class 1 {
         bandwidth 128kbit
         match VOIP-RTP {
             ip {
                 dscp 46
             }
         }
         match VOIP-SIP {
             ip {
                 dscp 24
             }
         }
     }
     default {
         bandwidth 327kbit
     }
 }

ubnt@ubnt# show interfaces   
 ethernet eth0 {
     address 192.168.3.1/24
     description Local
     traffic-policy {
         out fair
     }
     vif 100 {
         address 192.168.1.1/24
         description dmzlike
     }
 }
 ethernet eth1 {
     description "Internet (PPPoE)"
     pppoe 0 {
         firewall {
             in {
                 name WAN_IN
             }
             local {
                 name WAN_LOCAL
             }
         }
         password foo
         user-id bar
     }
     traffic-policy {
         in lim1
         out fair
     }
 }

That constantly takes 128kbit/s off the bandwidth and keeps it available for VOIP.  It's not ideal because receiving data takes a bit longer due to the reduced bandwidth, but phone calls still work when the line is otherwise fully occupied.

I thought I'd share this in case there are others having problems with low bandwidth.  If there is a better solution, I'd like sure to hear it Image may be NSFW.
Clik here to view.

PS:  Perhaps I should do something else than a fair-queue with the upstream traffic.  I'm not sure what, though.

PPS: Using a smart-queue configured via the GUI resulted in phone calls being aborted after about 8--15 minutes.  Is that a bug or to be expected?