Hey all,
Received great help from here the last time we had an issue with our system and so here I am again!
We have call quality issues that have arisen at our remote office. The issue seems to be intermittent and only happens within this office. Our local office that is on the same network as the phone server and uses the same phones works just fine without any apparent issues.
The remote office has a T1 connection and is connected by Site-to-Site VPN over Sonicwall firewalls with bandwidth management setup to allocate 30% of its bandwidth to the phone traffic (SIP 5060-5062 & RTP 10000-20000). It has a Cisco SG00-26P switch and that’s about all there is up there. The phones are Polycom 501’s with one 601 model and all are using G711; both are experiencing the issue. Ping times to the phones average about 70-80ms from the phone server, across the VPN, to the phone. Firmware has been updated on the phones to the latest version as well.
Periodically throughout the day, some of the phones will experience call quality issues where audio is cut out and both the caller on the other end as well as the employee hear choppy audio. It is comparable to a cell phone when it has bad reception. It happens with both internal and external calls, but more often with external calls.
We have been monitoring the internet traffic, and although there are spikes in the traffic that max out the T1, they don’t correspond with the call quality issues except for a few hit or misses here and there. Right now, my next troubleshooting step is to try swapping out the switch with an extra one I have to see if it has something to do with the cisco switch’s settings (perhaps QoS?) We haven’t tried connecting the phones to our local office’s public IP but I’m not ruling it out as an option. I just like the Site-to-Site VPN since it keeps our phone server secure 
The system is running:
PBX Firmware:2.210.62-5
Asterisk (Ver. 1.8.20.1).
I’m still relatively new to reading through the logs and have been unable to spot anything that is glaringly obvious to me. (Doesn’t rule out the chance that I’m not seeing something that SHOULD be obvious to a vet) Let me know if I should post a section of the log that contains the alleged times the issues occurred at.
As always, I appreciate your help and thank you for taking the time to look at this!