A surprisingly simple cable modem replacement
There are tales of people who used to have phone equipment from Ma Bell pre-divestiture but kept renting it long after it wasn't necessary any more. They were paying monthly fees for phones which had long since been paid off many times, and could have been replaced for a trivial amount of money at a Radio Shack, K-Mart, or basically any other consumer electronics place of the day.
The same thing applies to cable modems. If you're new to the scene, you probably let them set you up with whatever they provided, and just pay a $4 or $5/month fee for the privilege of renting it. After a year or two, you've more than paid the retail price. After that point, everything they're making from you is pure profit.
Still, there can be reasons to stay with their official equipment. If, for example, you are using a special landline service through your cable company, you probably have a custom device which can't be replaced. They treat telephone service rather differently, and I can't argue with them too much considering how important E911 routing can be.
So, let's say you decide a land line is just a waste of money and give it the boot. Once you've done that, you no longer need their custom device and can do your own thing. I recently went through this, and here's how it works. Strangely, it isn't a disaster story.
First of all, you need to pick out a replacement. Given that my existing equipment was 6 years old, it wasn't hard to find something that was newer, shinier, and which hit all the latest buzzwords. I'll refrain from making a recommendation here because the gearheads will always have their own ideas about what works for them.
Next, you have to get it on the cable system. To eliminate any sources of wackiness, I removed my usual network rigging (router and whatnot) and went straight into my laptop from the device. I was able to watch it via the usual embedded web server on 192.168.100.1. It wasn't having such a good time. According to the log, it would start downloading the "walled garden" config (no surprise there), but then it would also time out during negotiations and would reboot itself.
A few seconds later, it would come back up and say "Disruption during SW download - Power Failure". Well, gee. Maybe if you'd stop shooting yourself in the foot, it would actually have a chance to download. I watched this happen a fair number of times and tried a few things in the hopes it would even out: let it boot disconnected from the cable, then connect the cable, click the "factory reset" button, and finally, disconnecting everything else from the cable. It happened to work at that point when my cable box and Tivo were disconnected, but that doesn't prove anything.
Anyway, now that it had managed to boot into the walled garden, I was able to get a DHCP lease from Comcast instead of my own cable modem, and that was enough to get to their provisioning site. Granted, I had to remove the custom stuff I normally have on my Ethernet port for a static IP address and recursive DNS servers, but that's just me. Once my machine was set to just trust whatever the network gave it, their site came up.
From there, it was just a matter of telling it my account number and associated phone number. It found that, greeted me by name, and then displayed what it was about to do: change modem X to modem Y. Then I could click "next" to proceed. At that point, it informed me it might take up to 10 minutes to complete this next step, and I saw why: the site had instructed my modem to reboot: "Cable Modem Reboot from shell". Fascinating, right? Automatic remote access.
So, I got to sit there and bounce back to the 192.168.100.x network while it rebooted and then saw it coming back up and downloading a normal (non-walled-garden) load. After that, I got a routable IP address again and the site confirmed all was well. It then told me to close the window and that was that.
Next I just had to disconnect my temporary rigging and park it behind my router, and finally bounced the cable modem to make it learn the right client-side MAC address. With this done, my router did its usual DHCP release/renew thing, and I was back on the air.
At no point did I have to deal with humans to get this done. They've come a long way since the days of "you must be running Windows 98 and you must install all of this bundled crapware to get online". They finally figured out that just using the web is the way to go.
As for the old cable modem, I dropped it off at a service center this afternoon. The rep scanned a bar code on the back, and that identified the account and who I was. She handed me a receipt and that was it. It should just disappear from my bill on the next cycle.
I guess I'm shocked that an interaction with the cable company was decidedly uneventful.
If you're still paying them a monthly fee for your device, don't. If you have an hour or so, you can get rid of it for good.