# Are cable modems pretty much the same? **URL:** \ **Category:** Factual Questions\ **Created:** [April 14, 2002, 2:50am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520 "2002-04-14T02:50:26Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [April 14, 2002, 2:50am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/1 "2002-04-14T02:50:26Z")
I want to stop renting my cable modem from the ISP and buy my own. So, is there a difference between modems? Or are they all pretty much the same? Here is the list of approved modems. 3Com®\* CMX 2940 3CR29220 3CR29221 3CR29223 Motorola® (Formerly General Instruments®) SB2100 SB3100 SB4100 Arris/Nortel® CM100 CM200 CM200u High Speed Surfing® SM100 BestData® CMX110 CMX100 Linksys® BEFCMU10 COM21® DP1010 DP101 DP111 DP1110 DOXPORT1110 Thomson/RCA® DCM105 DCM205 DCM215 DCM225 DCM226 DCM235 DCM235R DCM245 DCM245r D-Link® DCM-100 DCM-200 Toshiba® DAZ8801 DAZ8811 DAZ8813 PCX1100 PCX1100U Ericsson® HM200C Zoom Telephonics® 5011 - external model only ---
**Author:** ![mnemosyne](https://avatars.discourse-cdn.com/v4/letter/m/c4cdca/32.png) [@mnemosyne](https://boards.straightdope.com/u/mnemosyne)\ **Post date:** [April 14, 2002, 4:20am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/2 "2002-04-14T04:20:48Z")
I’m not sure of the reasoning, but I know that when my SOs parents swtiched ISPs, they had to get a new (different) modem. Whether they were significantly different, or the new company was just being bitchy, I don’t know. But they were able to buy the first one off of their first ISP, and lucky us, its the same one used by the provider where my SO and I live, so hopefully we;ll be able to just get the service and not pay for a new one. Not that that really answers your question…🙂 But I’d say if you’re planning on sticking with the same provider, see if you can buy it off them. ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [April 14, 2002, 10:18am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/3 "2002-04-14T10:18:28Z")
There’s a cable modem standard called DOCSIS which all those cable modems should be compliant with. However, the cable company can selectively allow or disallow specific cable modems from being authorized on the network. The reason they have a list of supported cable modems is that those are the ones they know how to help you with if you have trouble. If you pick one not on the list, they very well may refuse to authorize it, so it won’t work. ---
**Author:** ![Muad\_Dib](https://avatars.discourse-cdn.com/v4/letter/m/35a633/32.png) [@Muad\_Dib](https://boards.straightdope.com/u/Muad_Dib)\ **Post date:** [April 14, 2002, 4:41pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/4 "2002-04-14T16:41:11Z")
So, there will be no difference in speed and reliability? None of them have special features? ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [April 14, 2002, 9:18pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/5 "2002-04-14T21:18:23Z")
> [@](#): > > \*Originally posted by Muad’Dib \* > \*\*So, there will be no difference in speed and reliability? None of them have special features? \*\* Oh, no, there will certainly be reliability differences and different features available for all those different modems. My point is simply that they’re all technically capable of working with your cable modem signal if the cable company wants to let them. ---
**Author:** ![tspallone](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@tspallone](https://boards.straightdope.com/u/tspallone)\ **Post date:** [April 15, 2002, 7:53pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/6 "2002-04-15T19:53:32Z")
Also, you should make sure that the modem with work with your particular OS. ---
**Author:** ![ChronosGF](https://avatars.discourse-cdn.com/v4/letter/c/7ab992/32.png) [@ChronosGF](https://boards.straightdope.com/u/ChronosGF)\ **Post date:** [April 16, 2002, 6:45am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/7 "2002-04-16T06:45:45Z")
Wouldnt the MAC address have something to do with this? Im not really sure what it is or what it does, but there’s little sticker on my cable modem with a MAC address on it that my cable company sometimes asks for if I call. ---
**Author:** ![mblackwell](https://avatars.discourse-cdn.com/v4/letter/m/5fc32e/32.png) [@mblackwell](https://boards.straightdope.com/u/mblackwell)\ **Post date:** [April 16, 2002, 7:06am UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/8 "2002-04-16T07:06:45Z")
> [@](#): > > \*Originally posted by ChronosGF \* > \*\*Wouldnt the MAC address have something to do with this? Im not really sure what it is or what it does, but there’s little sticker on my cable modem with a MAC address on it that my cable company sometimes asks for if I call. \*\* The MAC address is the unique hardware address of the modem. The ISP keeps a list of customer’s MAC addresses, and only allows MAC addresses on the list to get an IP from the DHCP server. This keeps people from buying a modem and getting service without paying. ---
**Author:** ![Running\_with\_Scissors](https://avatars.discourse-cdn.com/v4/letter/r/a183cd/32.png) [@Running\_with\_Scissors](https://boards.straightdope.com/u/Running_with_Scissors)\ **Post date:** [April 16, 2002, 4:22pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/9 "2002-04-16T16:22:30Z")
The type of modem you buy can also affect the connection speed, just like a standard phone-line modem. Operating system support is usually not an issue, as pretty much all of them use Ethernet to communicate with your computer. Some also offer USB, but Ethernet will give you better performance. You might want to check out [www.dslreports.com](http://www.dslreports.com). Personally, I’d recommend staying away from any 3com modems because they’re getting out of the business. ---
**Author:** ![Mr.Slant](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mr.Slant](https://boards.straightdope.com/u/Mr.Slant)\ **Post date:** [April 16, 2002, 4:43pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/10 "2002-04-16T16:43:30Z")
When my local cable ISP was having issues, I called tech support. A lineman was sent out to work on my line. The real issue later turned out to be at the larger network level, however during troubleshooting he took my 1st modem, a Toshiba, and replaced it with the one I have now, which is a Motorola. He claimed that the Motorolas in general have higher performance when confronted with less than 100% perfect connections over the cable. Was he right? I don’t know. But I wanted to share this with you in hopes it might help you make a good decision. ---
**Author:** ![batsto](https://avatars.discourse-cdn.com/v4/letter/b/b2d939/32.png) [@batsto](https://boards.straightdope.com/u/batsto)\ **Post date:** [April 17, 2002, 1:23pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/11 "2002-04-17T13:23:57Z")
Just because a modem is DOCSIS certified does not mean your ISP will allow you to use it…I know this as I work in the modem dept. for Comcast and we have a list of modems that, while DOCSIS approved, are not Comcast approved and we do not allow their use on our network. ---
**Author:** ![Why\_A\_Duck](https://avatars.discourse-cdn.com/v4/letter/w/13edae/32.png) [@Why\_A\_Duck](https://boards.straightdope.com/u/Why_A_Duck)\ **Post date:** [April 17, 2002, 1:37pm UTC](https://boards.straightdope.com/t/are-cable-modems-pretty-much-the-same/103520/12 "2002-04-17T13:37:56Z")
> [@](#): > > _batsto said it_ > **… I know this as I work in the modem dept. for Comcast …** In the next few months as I begin to deal with the broadband idiots -er- customer service reps at illegal-cable-monopoly -er- COMCAST, I will try to remember that there be dopers there somewhere and that I should try to be civil.