Standard jacket with a twist: a (presumably conductive fabric-lined) inner pocket blocks cell phone reception. Wonderful tool not just for getting some ‘quiet time’ but for ensuring your personal tracking device that makes calls does neither.
You can make your own, too, should you want to upgrade that red velvet smoking jacket: conductive fabric is widely available thanks to the wearable computing branch of the “Maker” movement. There’s even conductive thread for ensuring the seams are RF-tight. (still looking for conductive velcro, which you’d really need for a proper seal)
Fabric is surprisingly useful elsewhere for security, too. I’ve mentioned before that you can create a fairly secure improvised seal by photographing a towel* from a precisely reproducible position. If you take a second photo sometime later, then use the in-camera crop function to make two zoomed-in copies of the photos, you can switch between the two and precisely tell whether or not the towel’s been disturbed. (the large, coarse fibers make it pretty clear.)
* particularly a towel hung over a doorknob or cabinet. doorknobs come with handy door jambs opposite them which are wonderful for precisely placing the camera.
I’ve tried a variety of attacks on this, mostly oriented towards sliding something under the towel to hold it in place, but I have yet to find a defeat that even halfway succeeds.
“The idea is that as soon as you leave work, or just want a break you put your phone in the inner pocket of the jacket and you terminate all connectivity. By using the pocket as an off switch you make mobile communication a bit more tangible, there is something very satisfactory about being angry and throwing your phone in your pocket to end a call. Bu using the principles of a Faradays cage the pocket is effectively blocking all radio frequency waves. An NFC chip embedded in the fabric turns of the phones antenna to save you that precious battery time. “