Telephone lines almost always have an externally accessible demarcation box at ground level (usually a little grey one that says "telephone wiring" on it), making them very easy for a crook to cut. Cable varies a lot, though. It's common for cable to be retrofit into older construction in such a way that the lines are externally accessible, but in newer houses it may have been installed at construction time and well hidden. The cable splitter/distribution amplifier is often in the basement or elsewhere in the house, but is sometimes also installed on the exterior, basically depending on what was easiest to the installer.

So basically, there's almost no common standard for cable. You'll just have to look around. Sometimes the incoming line is lazily run along a fence, sometimes it's buried and all house wiring is internal.