ok i am trying to get a sierra 750 aircard to work under slcakware linux

t-mobile doesnt support this , but sierra says they have tested it under red hat , and everything seems to be working except when i try to connect all i get is ...
a bunch of modem strings? (sent and recvd lines)
then
"appear to have rejected your own echo-reply!"
then modem hangup...

the air card is a pcmcia device with linux configured to treat it as a serial device....

would appreciate any help
adian