"NO CARRIER" when dialing using ATD

[samraj]

Hi,

I have a PCMCIA modem-card used in a linux laptop. When I try dialing
to a mobile using the ATD command for eg: ATD 9845207728 I get a
response NO CARRIER.
what does this mean?. when I try the same on a windows laptop it
works.
Plz let me know what are the settings required to solve this.

Thanks and regards,
sam

[Art Jackson]

samraj wrote:

NO CARRIER means you didn't connect to a modem on the distant end, or it
timed out before a successful handshake and connection could be
established. You should specify the type of dialing you want to do with
the ATD command. ATDT =Tone dialing, ATDP =Pulse dialing. Some modems
DONOT support pulse dialing at all. What speed is the mobile modem
capable of? If it's something like 9600bps, and you are dialing with a
56k type modem, the additional time it takes for your modem to negotiate
a connection may be too long, therefore it drops the connection and
reports NO CARRIER. When dialing into low speed modems, it's best to
disable all 56k protocols on the dialing modem, to shorten the handshake
time. A less desirable remedy is to increase the time to wait for a
Carrier by increasing the value of the S7 register. Default is usually
60 seconds, so S7=90 in the init string, would add another 30 seconds
for the modems to do their handshaking and establish a connection. Of
course, the mobile modem may be dropping out. I don't know how much time
it would allow for a connection to be established. For that reason, it's
best to disable the 56k protocols, and even V.34 when dialing a 9600 or
14,400 modem. Good luck.

--
Art Jackson W4TOY Owensboro, KY USA
Life is God's open book test. In order to pass,
you must open His book to find the answers.