Hi, We're looking at implementing a 3CX phone system and we're a bit confused about the upload speed required. We currently have a Panasonic VOIP system, and we have 8 lines running off an ADSL2+ with 10mb download and 1mb upload speed. It works perfectly, and we NEVER have any call quality issues. We are interested in putting in a 3CX system so that we can join three offices together, and have the sites integrated, for a total of 13 lines, with 5 of them remote from the IP-PBX, with more remote lines possible in the future. We have checked with about 4 different Panasonic dealers who all say that we need a much faster upload speed for this scenario. We have checked with multiple 3CX dealers who all say it will work perfectly. In both cases they are talking about the same codec - G 729a I think. But one side says to allow for 100KB or more and the other side says 40KB is fine. The explanation I had from a Panasonic dealer is that it's only around 40KB needed technically, but in their experience in the field we should be allowing for 100KB at least to ensure reliability of call quality. As far as I can tell there is only two options - Panasonic dealers are overly conservative and/or 3CX dealers are not conservative enough, (the ones we've spoken to anyway), or there is some technical difference between the two systems in terms of the bandwidth required. Can anyone shed any light on this? Any help would be GREATLY appreciated!!