Guys,
there is no real magic behind those updates. iPhone-OS comes with a set of carrier bundles for Apples legit partners. Carrier bundles predefine options the carrier offers to the customers like APN, MMS data, Voicemail number and so on. Sometimes a carrier wants to change the service. Maybe use another APN for tethering to be able to charge you, or just add MMS functionality. In this case the carrier and Apple create a new carrier bundle.
All bundles have couple files and logo pics inside. One files - Info.plist - has a field with the version number of the carrier bundle.
Apples Server host all updated carrier bundles. Once you connect the iPhone to iTunes, the server is contacted, zillions of informations flow between your iPhone and Apples server. One information ist the version number I mentioned. If Apple has a newer one on the server - boom - the update is offered.
When applied it may exceed the service you already have, but may restrict it aswell. But it will never offer unlock, activation or other stuff.
This only applies to users with a legit contract. For hacktivated on a non Apple carrier: Once you create your own carrier file for your provider, you may choose any version in Info.plist. It wont be updated ever cause Apple does not cover the carrier.
If you are on a legit carrier and modify your carrier bundle to meet your needs (aka stealth tethering, enable MMS) just make sure to grab a significant higher version number for Info.plist. If the actual is like 5.6 I'd go for 6.5 or 8.0. In this case you'd "miss" the next official updates that would ruin your home grown cb.
Sorry for the long post, just wanted to explain what cb's do and dont.
BTW, along Orange on November 3 the following carriers got automated updates: Bell_ca, Hutchison_it, One_at, Orange_ch, VOX_lu