RE: Forcing modem to dial in absence of dialtone

["drew cohan" <debian@drewcohan.com>]

Hi,

>The problem is that they have a telco-based 'answering
>machine' which signals the presence of waiting messages
>with an intermittent dialtone. The modem thinks this is an
>invalid dialtone, reports NO DIAL TONE and I cannot dial out.

If you're using pppconfig, there's a place for extra AT commands.  What you
want is X1 (from http://www.option.co.za/hayesat.htm#Hayes%20AT%20Commands):

"ATXn Extended Result codes

X1 Ignore dialtone and busy tone
X2 Ignore busy tone
X3 Inner dialtone
X4 Modem recognises dialtone and busy tone

X3 and X1 set the modem for Blind Dialing. This option is country specific,
because some countries do not allow blind dialing."

If not, try both X1 and X3 like they suggest.  I think all I've ever had to
use was X1 when I was in your situation.  And for kicks, throw in S11=50 or
S11=55, which will reduce the amount of time to 50 or 55 milliseconds
between DTMF pulses (less waiting for the phone number to dial, 50 is the
absolute minimum).

Good luck,

Drew
debian@drewcohan.com