USBModem-LTE-3G-4G-Raspberry-Raspbian-

Connecting to internet on a Raspberry Pi 3B+ (Raspbian) Via USB modem LTE/4G/3G ZTE MF821

1. Install Modeswitch

# apt-get install usb-modeswitch usb-modeswitch-data modemmanager

2. Install wvdial and minicom

# apt-get install wvdial minicom

3. Change wvdial.conf

on /etc/wvdial.conf input the following.

[Dialer Defaults]
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

#Replace "internet.comcel.com.co" for APN 
Init3 = AT+CGDCONT=1,"IP","internet.comcel.com.co"

#Replace for the ones specific to your carrier
Username = COMCELWAP
Password = COMCELWAP
Phone = *99#

Modem Type = Analog Modem
Stupid Mode = on
Baud = 9600
New PPPD = yes
Dial Command = ATDT

#Replace for wherever your USB STICK MODEM is mounted 
Modem = /dev/ttyUSB2
ISDN = 0

Run usbconnect.sh

Remember to change permissions

sudo chmod +x usbconnect.sh

Then run it.

sudo ./usbconnect.sh

You may need to do this after:

route add default dev ppp0

This sorts out the routes for internet access.

Run a classic ping

ping 8.8.8.8

---

UNDER VALIDATION

1. find out the modem's idvendor and idProduct by running $ lsusb

   i.e Bus 003 Device 003: ID 19d2:0257 ZTE WCDMA Technologies MSM
   

Pay special atterntion to 19d2:0257

2. Go to /lib/udev/rules.d/40-usb_modeswitch.rules and add the following entry:

# ZTE MF821 4G LTE
ATTRS{idVendor}=="19d2", ATTRS{idProduct}=="0257", RUN+="usb_modeswitch '%b/%k'"

3. create file called: 19d2:0257 ({idVendor}:{idProduct}) in /etc/usb_modeswitch.d/ and add the following inside that file (remember to change the values for your own:

# ZTE LTE 4g modem
#
DefaultVendor=  0x19d2
DefaultProduct= 0x0257

TargetVendor=  0x19d2
TargetProduct= 0x0257

MessageContent="55534243123456782400000080000685000000240000000000000000000000"

CheckSuccess=20

4. make network manager recognize the device automatically. add this line to your /etc/rc.local

modprobe usbserial vendor=0x19d2 product=0x0257

DEEPLY BASED ON INFORMATION FOUND HERE: https://ubuntuforums.org/showthread.php?t=2074518