I have a few questions regarding the pros and cons of moving a locally installed 3CX PBX in an office to a datacenter. I already have a few ESXi servers running in a local datacenter with more than enough capacity to run either just this PBX or even the multi tenant version. I have a client who up till now had just one office with an internal 3CX PBX using a 2MB SDSL line. This office is in Central London but the SDSL connection has not been great and they have had to change a number of times to a dedicated backup ADSL connection which obviously on another IP address and this breaks the 3CX tunnel connection. The office is with a couple minutes walk of the Mayfair exchange but the connection length is around 1.5km and I'm told it's the routing and some of the wiring maybe old. So they have 3 internet connections at the minute into the office a ADSL2+ data connection for their computers, a SDSL line for phones and an ADSL backup line. I've also recently seen an article in PC Pro where the head sales guy for the company that supplies these lines said that the SDSL product has never been great. With the introduction of BT Infinity etc I have been asked by the client if they should also be looking to upgrade. They have now had another office open in Central London and are currently using the 3CX Tunnel to connect the phones from the other office to the PBX. Some calls through this tunnel have had quality issues mainly I think due to the calls going over this SDSL connection twice. Is moving this 3CX to the datacenter the best way forward? If this was done is the best way to connect the phones to the PBX the 3CX Tunnel or directly? My thinking is that by moving to say 2 BT Infinity lines with 70meg down 20meg up and introducing a dual band router with QoS and failover etc then if there was a problem the switch over would be automatic. At the moment they have to physically go to the cabinet and switch modems from the SDSL one to the ADSL backup one and they are not very technical. This would also actually be cheaper than having the SDSL line which alone is about £100 a month. I know the SDSL line has a lower contention ratio but with the issues they are having with it and the branch office layout is this a better option? Each branch office would then have a direct connection to the PBX which is centrally hosted in the datacenter. Is this change a no brainer with this setup? Is BT Infinity good enough for SIP, this company only have the Professional Edition with 16 simultaneous calls. Anybody done this before or any thoughts would be appreciated, thanks.