SSH is blocked from the outside. We have both PRI and SIP, but SIP accounts for 99% of incoming calls.
The switches are Procurve 5406's and the phones are on their own VLAN (same as system) with QoS enabled. If I have bandwidth issues on these $5,000 switches, I have a big problem.
We do record conversations, but that's done via Tracer.
What's G.729? We do not have the PS1, but CPU usage is normally under 25% (I don't know if that's a good indicator or not)
We do get insufficient bandwidth warnings once in a while since these issues started, but that's not normally something we see.
If it helps, here's a list of ports open to the outside
tcp-udp/69, tcp/3998-3999, tcp/44000, tcp/5566, tcp/6800-6802, tcp/6880, udp/20001, udp/5004-5007, udp/6004-6261