Back in Mass, USA Comcast went to all digital encrypted in my town and you had no choice but to get their box(es).
As to the odd channel numbers, that's Digital TV for you. Nothing new unless someone just arrived from a few year hiatus and were not exposed to the new channel numbering. It's Comcast's choices to put what on what channel so part Comcast and part how the new world order of HDTV is.
Comcast usually installs such things and you ask questions like that of the tech or just use google. However once in a while you find an old school client that tears into anyone that suggests that we research such things online.
Just connected new Samsung UN19F4000AF TV to Comcast cable in bedroom. After setup has started the menu eliminates "scrambled" channels and I end up with few working channels and they are mostly unwanted crap. The channel #s are weird (like they have been put into categories, i.e., 18-1, 18-2, etc.) The "manual" does not cover some menu items and I'm totally confused on things after "Cable. Such as the selection of "DGs" or should I use "Std". Are there any step by step instructions out there or does Comcast create this problem on purpose?