OS 4.0
Blackberry TCP Setting: APN= wap.cingular
Name=
Password= CINGULAR1
Modem Extra initialization commands: +cgdcont=1,"IP","WAP.CINGULAR"
Modem Speed: 115200
Hardware features: enable hardware flow control
enable modem error control
enable modem compression
Phone number: *99#
TCP/IP: obtain IP and DNS server address automatically (no manual DNS server address needed)
Advanced TCP/IP Setting: enable use default gateway on remote network
disable use IP header compression
Error 734 was solved using wap.cingular,
for both modem and Blackberry TCP.
Good Luck!