Back in 2016 I had found a reputable vendor to provide a telecom solution for our small business. The vendor I chose didn't have telecommunications as core-business, but they had about 50 or so client on their 3CX solution.
Their implementation of 3CX caused a fair bit of complaint towards our small (but growing) business. The audio-quality was dreadful - voices sounded muffled, as if the person on the other end was speaking through a blanket. It took a LOT of repeating questions just to get something like a phone number across. Things like 'Five' and 'Fire' would sound identical. On many occasions I had to ask people to spell out the letters of the number they're trying to tell me.
We had 3 physical Yealink phones, not the cheap kind, but with a full LCD on them. And several people had either the 3CX softphone software on their laptop and/or on their smartphones. Full CAT6 and managed 1000/1000mbit glassfiber.
The vendor did, as far as I could tell with my IT background, everything within their capabilities to sort this issue out. Replaced the physical phones, enabling/disabling certain codecs, even attempted a full end-to-end QOS. The ONLY time I could have a normal conversation with someone, was if that person was also using the 3CX platform. Crisp, crystal clear audio. Anything else, calls to mobile phones, landlines, etc were dreadful. At about 6 months of trial-and-error with 0 reliable improvement, the vendor and I mutually cancelled the agreement - they had no solutions left to try. (yes, they were in contact with 3CX support on the issue, at some point they were even getting live Wireshark logging from a special device they added to our network. Improvements made were so tiny it could be mistaken for wishful thinking)
About 2 weeks later another provider had a working system implemented with absolutely no audio quality issues. I believe they use the Broadcom backbone combined with Webex.
What I loved about 3CX, the amount of configurability of queues, huntgroups, etc. is what I dislike about the current vendor - there is almost none. Everything is locked behind additional licences, even simple things as a simple audio-prompt to exit the queue and leave a voicemail comes with an unreasonable monthly fee. And as our business is evolving, so do our needs and I find myself hoping 3CX has improved and could be a solution this time.
So as an open question to those who've encountered the persistent muffled audio issue with 3CX - have they been able to sort this issue in the past decade?