The communications system in the XF is a bit of a mixed bag - it's not like it's particularly bad at anything, just that it doesn't have quite the same polish as the navigation and entertainment modules.
Obviously you get Bluetooth phone support, which had no problem connecting to my iPhone, or any other handset that I threw at it for that matter. However, unlike the system in the Audi A8, the XF doesn't offer automatic voice dialling for your entire address book once you've paired your phone. Instead you have to record individual voice tags for each contact that you think you'll want to dial while on the move.
Recording your own voice tags isn't necessarily a bad thing, since it means that you can pronounce each name properly and not have to remember how the system thinks it should be pronounced. What is a bad thing is that you can't simply hit the voice control button and say "Dial Andy", instead you have to say "Dial Name" and then when prompted for the name say "Andy" - assuming you know someone called Andy of course.
On the plus side though, call quality is excellent is excellent in both directions, with most people I talked to not even aware that I was using an in-car hands free system at all. Obviously this is helped by the superb sound insulation in the cabin, but even so, the XF put in one of the best hands-free call quality performances I've encountered.