Okay, so I made a couple of changes as I realised that the firewall filter for the Classifier appears to be for unmarked traffic that can be marked upon Egress.... so, I just left in the DSCP command and pointed it to the voice queue. Again, no difference. So I tried with a VoIP phone sending SIP traffic unmarked and used a firewall filter and classifier. I got really weird results with this....
1: It made no difference to the traffic. It still ended up in the Best Effort Queue.
2: When the Classifier was applied to the ingress interface, I lost the eBGP peering..... When I removed the classifier the BGP peering became "Established" again. ---- That's weird.
So, does anyone have any idea why the eBGP peering relationship would be affected by the classifier?