Nortel SR1001 QOS Setup

[oldestgeek]

I have a 1002 connected to a 1001 by a full T1 point-to-point circuit. I have an Avaya CM 8700 at the main site and a gateway at the remote end. We're getting some jitter and the calls at times sound like a bad cell phone call. A continous ping across the link reveals the delay is 8-12 ms with no dropped packets. Here is the bundle configuration on the main site SR1002:
interface bundle Branch1
link t1 1
description "T1 to Branch1"
contact
encapsulation ppp
ip address 10.10.10.1 255.255.255.252
ip multicast ospfrip2
qos
add_class voip root-out cr 512 br 768
add_class default root-out cr 1024 br 1152
class voip
add_dscp ef
add_dscp cs6
exit class
class default
add_dscp default
exit class
enable cbq outbound
exit qos
red
exit red
exit bundle

And here's the config from the branch 1001:

interface bundle HQ
link t1 1
description "T1 to HQ"
contact
encapsulation ppp
ip address 10.10.10.2 255.255.255.252
ip multicast ospfrip2
qos
add_class voip root-out cr 512 br 768
add_class default root-out cr 1024 br 1152
class voip
add_dscp ef
add_dscp cs6
exit class
class default
add_dscp default
exit class
enable cbq outbound
exit qos
red
exit red
exit bundle

Data traffic seems to be flowing okay and when I look at the QOS queues, I see about 20-30 kb of traffic in the VoIP queue per call in progress. Does this setup priortize VoIP or just reserve bandwidth? How can I improve performance?
Thanks.