I now have a SIP URI on my business card - it is actually shorter than my phone number by quite a bit :-) I am showing the phone number as well.
It is a bit of an experiment to see if people ever use it, and obviously is a bit geeky.
But it does strike me as progress - it is a way of calling me that does not involve a telco or OFCOM.
That means no Data Retention Directive records for the call at all.
I think we may want to do a wiki page on how to set up your domain and FireBrick to accept SIP URI based calls directly.
At the moment it is a tad messy - a real SIP phone tends to want to call numbers, and via a proxy, so I can get calls but can't yet call people back. I suspect we'll refine this a bit over time to make direct SIP URIs easier to manage.
All good fun.