You are absolutely right, NO CELL PHONES should be allowed into any government facility that handles classified documents, PERIOD.
As to secure facilities, they aren't. Many have a nice little shelf or bar outside the secure area for you to lay them to or clip them on. Lots of pictures with slashes through them so even senior Democrat operatives can understand what is and what is not allowed. Basically anything with memory that can be written to. Some facilities won't even let you take such things as CD players, although others will. Cameras, digital, cell phone or old fashioned film, are a definite no-no.
Sandia National Lab and Los Alamos National Lab prohibits bringing any cell phones onto its grounds, as well as pagers and any other transmitting device. In addition both facilities prohibit bringing in any outside computer (how well this is enforced can be questioned thanks to the latest scandal. Some of this can be blamed on University of California's management, but the bulk of the problem IMHO lies with Hazel O'Leary's weakening of the labs security to meet her PC whims)