I just did a search on this, and there is not consensus on it. I was listening to a radio program a few years ago, and they talked about this for several days. I accepted that at face value, and repeated it here. Now that I've done a little more research, I'm not so sure. Thats misinformation becomes conventional wisdom, and I'm duly ashamed.
That said, I stand by what I said about using the phone. If you need to communicate electronically, do so online and use proxy servers. I use
www.hidemyass.com and can go into a chat room, here at rollitup or a private chat room elsewhere, and not be tracked. For added security, I can encrypt my data in case my pc is seized, or ecrypt my email to protect me if it is intercepted. My point is, I can communicate with near 100% safety via computer, whereas via phone the police can see who I'm calling, track my location, and with a warrant listen in.