I was designing an encounter hook for the party's Warden character and realized that I haven't the faintest idea what the routine method of communication is for the White Council and Wardens.
Obviously, things like phones and fax machines are unreliable, but worse, they are likely to be insecure. Wizards are unlikely to be experts or current on technology, and therefore be unfamiliar with how easy some of it is to tap into. And if they use pure human agents to handle the communications they have to deal with the issues of those agents having less defenses against supernatural subordination and deception.
I can see thaumaturgical rituals being used for contact. Maybe a 5 minute ritual if you have things like the persons address, a photo, something handled by them. Perhaps they have contact items that are kept in carefully sealed containers so preserve their thaumaturgical properties.
But that is one person contacting one other person. I can't see wizards doing blast faxes to everybody on their contact lists. It might be that wizards USED to have major advantages in long distance communications. They could probably do transcontinental communications through the Nevernever centuries before the invention of the telephone. A five minute ritual and you can contact anyone you know very well. But contacting everybody on a friends and acquaintances list is a different proposition indeed.
So, how does it work?
Does the White Council use fax machines and phones and computers and just use wizards who are sufficiently disciplined that the technology doesn't blow up around them as much? Does it use supernatural allies or pure humans who have long family connections? Does it use magitech, or is it mostly hopelessly behind the times in communications?
Some ideas:
Synchronized paper: What is written or typed on one piece of synchronized paper will magically appear on the linked paper or papers in Edinburgh or Regional offices. Yay! Wizardy bureaucracies. Please remember to use up or dispose of old paper before the link expires at the end of the lunar cycle.
Stereotypical magic mirrors. Constrained summoned creatures that transport letters through the nevernever. Or the White Council communicates fairly little, trusting the various autonomous Wardens and Regional Commanders to handle things on their own.