The customer mentioned in the previous post had 6 analog ports available on his PBX.
If he didn't, he wouldn't have been able to use the analog long range cordless phones as they would have been incompatible with the digital PBX.
Solution: digital-analog adapters. There are a couple of options.
Most phone systems have Analog Terminal Adapters (like Nortel's ATA2). These are a good option, but another option is the EnGenius digital to analog adapter.
Just another idea for everyone who needs to add analog equipment to a digital phone system. This will work for fax machines, answering machines etc.