Traditional FAX machines can be connected to the PBX platform using a FAX converter. This device converts the traditional RJ-11 plug into a RJ-45 plug, which can be connected to the network linking it to the VoIP platform. The FAX number can be transferred (ported) to SIP, making the traditional FAX line redundant.
Nothing changes for the users, as faxes can still be sent and received from the device in the usual way. The physical location of the FAX also becomes irrelevant with VoIP technology, as it will function from any location that has a network connection to the PBX server.
There are quite a few FAX converters on the market and both quality and prices vary greatly.
Please note: Not all traditional FAX machines are able to function correctly with SIP as problems may be encountered when trying to convert a connection to a very old FAX machine.