Netopia R5300 T1 - Any QOS Settings or Priority Queing

I have found the one setting in the configuration about prioritizing
delay sensitive data, but not much else on the router...

Background: Have a client who added a Barracuda spam filter to their
network, and redirected their email (10,000+ a day) from their ISP to
their 768k fractional T1.... On this same T1 they also have an Axxess
VOIP setup for their remote offices. Router is a Netopia R5300 T1.

Problem: Since the introduction of the Barracuda, DNS calls and SMTP
traffic seem to have congested the circuit a lot, and voice users
complain of call cutting out. T1 provider reports that the circuit is
not at full utilization, but that there is a lot of DNS traffice being
generated from the Barracuda. In looking at the configuration of the
Netopia I see no way of prioritizing data by port/protocol (like you
would find in a Cisco)...

Question: Am I missing something here... Is there some way to give
VOIP priority on the router over DNS and SMTP traffic... or am I stuck
with the one yes/no checkbox for prioritizing time sensitive data?

Any guidance would be appreciated.


Regards,

Andy