Digital Modems

Morris, Scott A. ( (no email) )
Wed, 16 Apr 1997 21:01:18 -0400


You have missed a few points on digital modem boxes.

On the config that you sent out the list, you have locked them into analog
forever! Even th old AS5200 had several distinct advantages over "A Cisco
2511 with 16 Cardinal

Your statement "I think the attractiveness of a
pre-boxed unit like a 5200 is the size and only one power plug, instead of
17." leaves out the fact that most any of the modern digital modem boxes
has the ability to have a T1 or PRI card. In either case, the D/A
conversion takes place on your box and not the telco's box. Personally, I
would rather deal with a single T1 or PRI than 24 POTS lines any day. With
todays technology, you can easily get more than 24 channels from a single
T1 or PRI service. Plus you get the advantage of doing analog and digital
connections on the same box.

If some new startup is watching the list, they should at least be guided
into an open ended box like an Ascend Max 200. They can start with POTS
(using PCMCIA modems) and start to move digital with BRI cards in the same

While "the user calling in is sending out ANALOG signals" you don't have to
get them that way. From the point that the caller hits the first CO, SLICK
cabinet, DMS100 or whatever, an A/D conversion has taken place. While it is
not a true A/D of the data, the analog signal is now digital. If you would
like, the telco will convert it back to analog for you at your CO, SLICK
cabinet, DMS100 or whatever. Then you can deal with the problems of the
analog loop from them or you can give your users a fighting chance at
getting the best possible connection that their local loop will give them.

What is your answer to 56k technology? Plug in 56k modems at your end and
expect to see 56k connections when both of you are using POTS? Wrong
answer!!! Read the specs on X2 and from the 56k forum. As a service
provider, you MUST HAVE digital service for it to work.

You said "to go to a complete(voice and data) digital signal, which will
not happen in the next 10 years." While that may be the case in Jefferson
City, Missouri - it is not everywhere. Some areas of this country (and
others around the world) will not give you more than 30 POTS circuits. So
what do toy do then? Buy a digital phone switch and keep buying "A Cisco
2511 with 16 Cardinal modems" I don't think so.

The moral to the story is Think Small, Be Small. Ask some of the big boys
watching this list what their lives would be like without digital modems.

Scott A. Morris
Sr. Network Systems Engineer
Computer InterConnections
Phone: 941.425.8338