I 've read the KB and I wonder if it would be necessary to create a new VPN zone.
On site A my PBX sits within 10.1.5.0/24
On site B my VOIP clients are within 10.85.86.0/24
There is no 10.1.5.0/24 in site B and no 10.85.86.0/24 in Site A
So I was thinking of adding a numbered st0 in each site's trusted zone (to avoid inter-zone policies) and route 10.85.86.0/24 through st0 in site A and 10.1.5.0/24 through st0 in site B.