I never got any responses about the telephone tile, but I found an area in my basement where I can see a cross section: it's basically a clay block wiht walls of varying thickness, anywhere from 1/2 - 1 inch thick, with an internal cross-brace. I built the porch - I used a masonry bit to drill holes in the face of the block (about 2 minutes per hole)and inserted bolts with lag shields to hold the ledger. I was afraid I might crack the blocks as the sheilds expanded, but they didn't; the porch hasn't collapsed, and the building inspector looked at it and yawned as he passed it. lemme know if I can help you in any way: skmd@aol.com