Re: I am looking for a new PCI modem that would be recognized by Linux
From: Scott Hemphill (hemphill_at_hemphills.net)
Date: 27 Feb 2005 23:04:51 -0500
email@example.com (Moe Trin) writes:
> Which ones, and what was the limitation? The example you show above is
> 46 characters, and adding two for the 'DT' command, that's still under
> the 58 character limit on my USRs. I can see it would be a problem on
> an old Rockwell based 28.8 modem (got the manual, but not the modem) that
> had a limit of 39 chars including the AT prefix - an even older SIIG 14.4
> (again a Rockwell chipset) had a 40 character limit.
It's been awhile. I think I ran into a 40 character limit with an old
Goldstar modem on my father-in-law's Macintosh. When I was Googling
about the problem, I also found references to 36 character limits for
other modems. The slmodem implementation has a separate limit for the
AT command line--it has a buffer size of 64 bytes. The 32 byte limit
applies only to the dial string, without the ATDT.
> >I couldn't have fixed this problem with a Real Modem.
> Agreed, but I suspect if you were using /usr/sbin/chat to dial the modem,
> you could try
> ABORT BUSY
> ABORT 'NO CARRIER'
> "" AT&F0
> OK 'ATDT 1-800-123-4567;'
> "" \d\d\d\d\d\d\d\d\d\d\c
> "" 'ATDT 1-1234567890;'
> "" \d\d\c
> "" ATDT 1-888-555-1212
> and accomplish the same thing. The first three lines are the boilerplate
> initialization stuff, and when the modem responds to that, dial the number.
> The semi-colon at the end of the number causes the modem to return to the
> command mode for further stuff. The next line waits for nothing from the
> far end, then waits ten seconds (the string of \d) and does not send a
> carriage return (\c) and so on. Not very elegant, but I think it should
> work. The quotes around the first two dial command are there to protect the
> semi-colon, and may not be needed.
I tried something like this first, and the semicolon didn't work in the
slmodem implementation. (Do you need an ATX to let succeeding ATDs work
without a dialtone?) Anyway, it would have required a much greater
understanding of what was going on for me to implement the semicolon
-- Scott Hemphill firstname.lastname@example.org "This isn't flying. This is falling, with style." -- Buzz Lightyear