Issues with calls to remote pbx

[Blake Carter]

We have 3 locations connected by Sonicwall site-to-site VPN.
2 3cx PBXs

Site A is running on a VM with pretty decent specs. Running on Debian (Roughly 40-50 extensions)
The PBX at site A runs the extension at site A and Site C (remote extensions)

Site B is running on an i3 machine with 4gb of Ram. Running on Windows 10 (roughly 22 extensions)

When a user at site B calls an extension at site A or C the audio is choppy. Site B states every 3rd word drops. Site A does not notice it.
We have reviewed the network at Site B and found that the 2 primary switches were still 100mb. We have upgraded these to 1gb switches.
Site B is still experiencing these issues.

Any tips on what to tackle next? Should we update Site B's pbx to an i5 or i7 with 8gb ram?

 

[RJansen]

You problably did this because its the first thing i find when i use google for a solution.

ISSUE - PACKET LOSS OR QUALITY ISSUES FOR VOIP OVER VPN

• Navigate to Manage | VPN | Advanced ensure Enable Fragmented Packet Handling is checked while Ignore DF Bit is unchecked. Ensure Enable NAT Traversal is also checked.
• Navigate to Manage | VPN | Settings and Configure the VPN policy for the VoIP traffic. Under the Advanced tab, check the option for Disable IPSec Anti-Replay.

 

[leejor]

Unless you have the extensions set to PBX delivers audio, or there is transcribing happening, the voice packets should not be affected by the speed of the processors. Are you using the same Codecs, on the sets at both ends? Do you have audio issues when placing external, or internal (same PBX) calls? Is the VPN encrypted. I have seen reports of encryption causing some audio issues.