Had a situation where a customer is moving several users that had analog connections for fax machines to a building that only has a fiber link, no copper between the phone system and the new location.
They opted for and purchased SPA2102 Sip to Analog devices to provide the dial tone needed.
Set up is a breeze on the 3300, and slightly less easy for the device, but not complex or difficult. Mitel even provides an installation guide to set this up.
Voice and fax both work splendidly with settings as laid out in the guide. There is no painful time period of adjustment to make this work.
Just thought I would pass the word along to others!