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I wonder if a modem is required to be programmed when using with an internet provider? If yes, what is the purpose of programming a modem?

Do both a DSL and a cable ISP both require a modem to be used in an individual home?

For example, I have a Motorola modem

SURFboard Model:SB5101, 
Customer S/N: xxx
S/N? xxx

a coil of cable and a splitter from Comcast High-Speed internet Self-Installation Kit, which were bought 5 years ago, when I purchased Comcast internet service from its retailer With them, I was hoping to reduce the amount of fee by avoiding to ask Comcast people to come over to install. But I remember at that time Comcast sent its technician here, dismissed my idea of self-installation, saying they needed to use their own modem and charging me a hefty fee, and so my equipments have never been used.

I haven't been using Comcast for a long time. I wonder if my modem, cable and splitter (brand new, never used) are still good to use with an internet provider such as Comcast? If needed, we can ignore their policy and just consider the technology side?

Or they are not good to use and I must throw them away like trash?

Thanks and regards!

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up vote 3 down vote accepted

As to whether or not you can use your own modem, you definitely can. I am currently using a cable modem I purchased, with Comcast. You just need to call Comcast and let them know you'll be using your own modem, and they should ask you for information (like its MAC address). The first time you plug it in to the cable, it will have to download information, which can take several hours, so don't be surprised if it restarts frequently and won't let you online. Found this link about the cable modem provisioning process:

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I will confirm this, as I just had Comcast connected. The SURFboards should be supported devices and you can make sure by checking their list Self install is an option, so do not let them try to tell you otherwise. There is no reason to pay for something you can do yourself. – jb11 Jul 3 '12 at 14:27
Thanks! (1) What kind of information will be downloaded? What is the purpose of programming? (2) Does DSL also need a modem? Is it different from a modem for cable internet? – Tim Jul 3 '12 at 14:28
@Tim 1. I believe it's provisioning information of some kind. I'm honestly not sure, but it has to exist on the modem before you can connect. 2. You do need a different modem for DSL compared to cable. – fairct Jul 3 '12 at 14:30
@jb11: Thanks! Five years ago, my local Comcast told me I was not allowed to do it myself. They perhaps just tried to get money from my pocket. If do it yourself, how do you connect the cable from the outside to the inside of the house? – Tim Jul 3 '12 at 14:34
@Tim Sorry, I was assuming that your residence was set up for cable. If you do not have cable running to your house from the nearest relay, you may need to have them do that. If it runs to your house but not inside, they could probably do it more efficiently but I know people that have wired their own houses. You need to make sure that they service your area. – jb11 Jul 3 '12 at 14:37

If you are talking about Cable Internet, all you need to do is first verify that your cable company will allow you to use your own modem, and then if they do... once you purchase your own modem you supply them with the MAC address of the device. This will allow their equipment to recognize and communicate with the modem you purchased. This explains why the cable technician can walk in to your home after you place a service call, and swap out a faulty modem with any working ones that he has on the truck. He just calls in the numbers on the modem, and a technician at the cable company replaces the old information with this new stuff.

Think about it this way. Unless it is a combination cable modem/router, there is no administration panel or user configurable settings you can get into in the modem.

If you are talking about DSL or ADSL, that's different. Specific connection based information has to be entered into the modem. DSL modems actually come with router firmware built into them, and it is typically hard coded to only pass out ONE internal IP address. So, it is possible to purchase your own DSL modem, or even replace the firmware on some of the ones given out by the telephone companies, but the modem has to be configured specifically for the ISP that you are connecting to.

If you have ever connected a router to a cable modem, and examined the connection details from the router admin panel, you can see the external IP address... the one given to you by the ISP. If you have ever connected a router to a DSL modem and examined the connection details from the router admin panel, you will see you are getting an IP address like from the DSL modem.

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Thanks! What does "it is typically hard coded to only pass out ONE internal IP address" imply? Can I use my router to connect to the DSL modem to allow multiple internal IPs? – Tim Jul 3 '12 at 17:07
@Tim you absolutely can. What I meant by that is that with most DSL modems you must use a router in order to share the connection. There are a select few ISPs that provide DSL modems with their internal router firmware wide open. – Bon Gart Jul 3 '12 at 21:18

I think this depends on the ISP, and on the country.

In the UK I used to use Sky, and they would send out their router pre-programmed. The username of the router was based on the MAC address of that router, and the password was randomly generated. There was no way to get the username and password normally from the router without using specific software to get the information from the router. Sky also told me I couldn't use a third party router and had to use their own devices.

That said, when I left Sky and I went to Be Broadband, I had my own router. They helped configure it for me but this didn't need a username and password, just an IP address.

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