We are based in Belgium, with a couple of extensions in UK and Ireland. Call quality between extensions has been super. All extensions are Grandstream GXP2000, set to G.722 as first vocoder choice and PCMU as second choice.
When we opened an office in Singapore, we added 5 extensions there, all configured the same way. These extensions all suffer from bad lag (1.5 - 2 seconds typically) and some echo. This applies to calls between extensions as well as through the trunks. I have tried switching the vocoder choices around, and enabling audio bypass, but neither seems to make a difference.
I can't search on "lag" in these forums, by the way - apparently the word has fewer than 3 characters :-)
I realise that VoIP lag a large topic with many potential causes, but we have identical equipment connected to the same PBXes account, while producing very different call quality. can anyone suggest further troubleshooting steps or possible fixes?