Usb modem in this new era sometimes come with dual mode. as a storage media and modem. In BT 4 beta this function make BT4 beta unable to read the modem. This Usb modem Like Globe Trotter, ZTE AC Series, Hyundai Mobile MB-810 and the other.

BT4 beta doesn't seems detect any modemand just Storage media, so what you need is Download usb_modeswitch.
Sorry i can't post any url yet. Just use google.
Code:
wget ****************************usb_modeswitch-1.0.2.tar.bz2
tar -xjf usb_modeswitch-1.0.2.tar.bz2
cd usb_modeswitch-1.0.2
sudo make install
It's should show progres like this.
Code:
mkdir -p /usr/sbin
install ./usb_modeswitch /usr/sbin
mkdir -p /etc
install ./usb_modeswitch.conf /etc
The next step, you need to open usb_modeswitch.conf and edit it. This case i'm using ZTE AC2726. First Open usb_modeswitch.conf the way you like. i'm using kate for it. Search for your modem name, And remove the ';' on the front of any code on your modem section. What ? ZTE AC2726 doesn't there. no problem. i Just looking for usb modem that nearly same to ac2726. i found ZTE AC2710. i Just copy the note and paste it on the bottom of usb_modeswitch.conf. Then i change the name and Product id ffff to fff1. because my ZTE AC2627 product id fff1. It's like this.
Code:
########################################################
# ZTE AC2726 (EVDO) 
#
# Contributor: Wasim Baig

DefaultVendor=  0x19d2
DefaultProduct= 0xfff5

TargetVendor=   0x19d2
TargetProduct=  0xfff1

MessageContent="5553424312345678c00000008000069f010000000000000000000000000000"
Next step we need to detect what is you product id. (vendor and product number)
Just type

Code:
modprobe usbserial vendor=<YourTargetVendID> product=<YourTargetProdID>
then
Code:
usb_modeswitch
now check lsusb and dmesg.
in lsusb it's should show something about your product id.
and in dmesg it's show something like /dev/ttyUSB0 or /dev/ttyAMC0.

Next step do your job with wvdial or gnome-ppp or kppp or what program that you like. i choose wvdial.

Hope this is use full.

Search How to Wvdial or gnome ppp or kppp on other thread, this thread just for how to detect dual mode usb modem.

However if someone really need help, Contact me. Or replay this thread, i'll look what i can do to help.

Sorry for bad English.

Regards
JoeleZ