If your looking for dial-up modems (and if you are... I'm sorry.. LOL !) there is US Robotics, Hayes, or Startech. Dial-up modems are very inexpensive and simple to install.
If your looking for cable modems then there's Motorola, Cisco, D-Link, Linksys
If you buy a used cable modem make sure it's DOCSIS 2.0 compliant (the newest transmission protocol for ISP's)
There are a variety of companies that specialize in producing modem electronics. The companies are located mostly overseas. China seems to be the higher producer with at least 10 companies such as Beijing Inmidas, Noton Digital Company, and Sailaosi Furniture Making Company Ltd, just to name a few.
An average wireless modem costs between $60 and $120 at an electronics or large retail store.
An Apple USB modem can be purchased directly from Apple through their website. Alternatively, one can find this modem at an electronics store, such as Best Buy or Amazon.
Some cable companies do provide an all-in-one cable modem and wireless router. You must contact your cable company to see if they offer this and how you can exchange your current modem for a wireless one.
An individual can expect to find a Linksys modem at stores that sell electronics such as Radio Shack, Target, Best Buy, and the Walmart chains as well sell them.
The companies that make modem and router combos are Netgear, Centurylink, Qwest and Windstream. The price range is anywhere from 45.00 to 90.00. Overstock website is a good place to start looking the this product.
The Motorola Surfboard SB5100 cable modem can be purchased at most local electronics stores, such as Best Buy. It can also be purchased online in Amazon or NewEgg.
The GPRS wireless modem comes with a very good two year warrenty agianst manufacture defects. Sometimes you can also purchase a secondary warrenty at the electronics store that will protect the product for breakage.
Since this was posted under Cable Modems, I'm assuming that you are asking about the (Data Over Cable Service Interface Specification (DOCSIS) cable modem which allows different cable companies and different cable modem manufactures all to adhere to a uniform set of protocols and modulation schemes to allow for inter and intra market competition. Go to Wikipedia and search DOCSIS for more information if that truly was your question.
In Canada, NETGEAR can provide a 3G USB modem, in addition to the Bell Canada Novatel. Both modems can be purchased on eBay or at a discount price, Amazon.
Yes, the BSNL modem can be used with any other broadband connection that you have, and the same is the thing for other companies too. You should have no problem using it with whatever setup you have.
You need a wireless modem but you also need the internet connection. You should call your cable company for some options. Comcast cable lets you rent the modem from them if you have service already. New customers often get good deals at most cable companies.
There are many companies that you can order a wireless broadband modem from. You can order from Rogers, Bell, Cogeco, Best Buy, Future Shop, Cisco, Dell and even Net Gear.