We have a project with a modem. I have a program that will power up the modem and send various AT command to initialize 
and monitor the modem. I am able to register and establish a PDP. What I am trying to do now is launch pppd. The command
 line I am running is "pppd call attlte"

Here are the contents of attlte
/dev/modem2
115200
noauth
defaultroute
logfile /etc/ppp/le920-log
connect "/usr/bin/chat -V -f /etc/ppp/le920-connect"

Here are the contents of le920-connect
#!/bin/sh
ABORT 'BUSY'
ABORT 'NO CARRIER'
ABORT 'ERROR'
''    AT
OK    ATD*99***1#
CONNECT ''

This is what comes back on my console
OK

CONNECT
Serial connection established.
Using interface ppp0
Connect: ppp0 <--> /dev/modem2
Hangup (SIGHUP)
Modem hangup
auth.c: Connection terminated.
Serial link is not 8-bit clean:
All received characters had even parity