> Apparently the digital to analog conversion
> impacts data speed negitively and most
> users get 21 to 24 K connections.
We had this problem before with Channel Banks (Our phone company uses D4
Framing) and with a little tweaking we were able to get 26.4K and 28.8
connects most of the time with our 33.6K USR Courier modems. This was
pretty unacceptable. We got rid of the channel banks and have moved to
POTS. Now we get 33.6K's almost all the time.
> If I buy the new Microcom ISPort modems and
> plug them into my portmaster would the additional
> analog to digital conversion on the modem adapter
> make the connect speeds worse? Anyone have any
> experience with this?
No matter what you do, you won't get fast connects with a channel bank.
Because of the conversions (A to D at the CO and then D to A at the
demark) you loose enough bits to cause problems with "analog" modems.
Needless to say, I'll never use a channel bank again.
(BTW, D4 framing takes away more bits than ESF, but my phone company
wouldn't switch over to see if that would help. Looking into it, though,
I've found a lot of people having similar problems)
> ------------------------------------------
> Using a channelized T-1 for POTS is too
> expensive (same charge per line plus
> several hundred per T-1) and since I have
> many analog Microcom modems connected
> to portmasers and PRI costs more per line
> I don't want to go to PM3 yet.
> ------------------------------------------
The difference between channelized T-1 and Channel Banks is less D-A/A-D
conversions. This is really important to the modem world. <G>
Jaime Bozza
Nucleus Communications, Inc.