The voice packets were sent to 10.24.24.166(*), so you need to include it in the route to the voip wan. Presently they are sent to the wan710 and lost.
Since there aren't any real Internet sites in the 10.0.0.0 block, you could route almost all of that block to voip wan 711 and not lose anything, except that your wan IP is also in the 10 range. Expand the existing route that covers the SIP server to all of 10.24.0.0/16 should work.
(*) This IP is likely to be different on each call, within some range of the servers they have.