In my opinion, There are very few people with the motivation and ability to pull off a work from home IT job in any sort of company with more than a few IT guys. Through the years I can't think of a single person who was remote, that I'd hire to work remotely. I've worked in IT shops from size 3 to hundreds. We have 2 in my group right now, they're good and they work hard but it's still difficult to communicate with them because they're simple not in the middle of the action, everything requires 3 times the explanation because they haven't heard all the detailed chatter because I don't set up a conference call every time someone walks up to my desk.
We found that rotating one person through the office to handle all the "drive bys" from people who couldn't follow procedure and open a ticket, was enough...
And the rest of the IT staff off-site got a lot more measurably done by all objective measures once we got the drive by problem solved by taking away the temptation to "just go ask IT".
You're correct that a solid conference system you run and know works every time is a requirement for out of band emergency escalations though. We had an "IT911" bridge that was NOT given to anyone other than authorized interface staff between departments.
Worked really well. You HAD to have objective goals and measurements as a manager however, but that's something a manager should be doing anyway. In fact, it's the only way to counteract the human tendency to whine that "IT isn't doing anything!", and is required even when people are in the office.
Other than that the other mandatory item was all staff on IM whenever on duty and teeth behind the phrase "only IT management tasks IT staff with work other than the on-call person for each discipline."
Bottom line, it took a lot of discipline on the part of management. The staff didn't need anything but a network connection, and a solid VPN.
Having seen it and lived it I no longer believe the many excuses thrown out by lazy managers who don't want to build a proper process or metrics that tie to objective business goals.
As time goes on and more people live it, keep in mind it'll become a significant drag on finding quality staff. The good ones will actively hunt for W@H and you'll get the unmanageable and unmotivated ones, creating a perpetual problem you can't solve with the staff you end up with.
There were other minor but obvious rules... Your Internet is down today? Get your butt in your car and drive in. Internet works here. Of course, we had a day or two where the opposite was true, since our VPN went to the hardened data center (where the real work connectivity was needed) and not the offices, and the data centers were directly interconnected and not done on a hub and spoke network through the venerable office networks. So there's some infrastructure work and design thought that has to go into it, too.