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Modem types


Can you please let me know what are the common modem types used these days for Leased lines, FR etc. Are there any good links that I can refer too. I want to understand the different signals and buttons available in a modem. Also how does the ISP test the link by using loops. Any good reference to understand loop ( hard, soft) will be highly appreciated. Thanks in advance.


Re: Modem types

Hi Manoj,

First of all these days its more common to have 'in built modems for T1/E1) like we get T1 CSU/DSU or MFTs hence the Router could be directly connected to the Telco cable (or drop out).

As far as the Loopback goes, generally I have used Hard Loopback in which we use either Loopback Jack (for T1/E1) or Loopback Barrel (for DS-3 Links)

Further information could be found at

Kind Regards,

Wilson Samuel

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New Member

Re: Modem types

Dear Wilson,

Thanks for sharing your thoughts on this. Can you also give me some good reference to the modems used for links < T1/E1. Modem types such as mlln etc their functional and configuration/ testing. Thank you very much.