Nokia 6256 BT Dialup Networking

I've gotten my Nokia 6256 to connect to Quick 2 Net but not to the
Express Network/National Access (1XRTT) via my BT modem connection. Yet
I was able to connect to the Express Network with my LG VX4600 via USB
cable and Mobile Office dialup software. What is the difference and how
to resolve it? I used the following info for Quick 2 Net: #777, user
name: qnc, password: qnc; and the following info for Express Network:
#777, user name: <10-digit phone number>@vzw3g.com, password: vzw.