How to connect your Raspberry Pi to a 3G network

In this tutorial we will show you how to connect your Raspberry Pi to a 3G network using the Itead Raspberry Pi GSM Board (SIM800). This breakout board communicates to the Pi over serial, but as we know the serial ports of the Pi are initally already in use, so we will need to do a bit of jiggery pokery to free up the serial ports.

Free up your serial ports

First we need to edit the /boot/config.txt file

sudo nano /boot/config.txt

Add the following lines

dtoverlay=pi3-miniuart-bt
enable_uart=1
force_turbo=1

Now we need to edit the /boot/cmdline.txt file

sudo nano /boot/cmdline.txt

Remove all references of "console=", for example, if the line reads:

dwc_otg.lpm_enable=0 console=serial0,115200 console=tty1 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

Change it to:

dwc_otg.lpm_enable=0 root=/dev/mmcblk0p2 rootfstype=ext4 elevator=deadline fsck.repair=yes rootwait

Next, we need to edit the /lib/systemd/system/hciuart.service file:

sudo nano /lib/systemd/system/hciuart.service

Comment out the After= line (by adding the # symbol at the begining of the line) and add the following on a new line

After = dev-ttyS0.device

Comment out the ExecStart= line (by adding the # symbol at the begining of the line) and add the following on a new line

ExecStart = /usr/lib/hciattach /dev/ttyS0 bcm43xx 460800 noflow -

Update your RPi

Make sure your raspberry pi is fully up to date by running these commands:

sudo apt-get update
sudo apt-get upgrade
sudo rpi-update
sudo reboot

Installing the required software

Start by installing the ppp package

sudo apt-get install ppp

Now we can install a piece of software called sakis3g. Its a really easy to use program that'll allow you to connect to your GSM provider.

Start by downloading the Sakis3g package

sudo wget https://cdn.shopify.com/s/files/1/0176/3274/files/sakis3g.tar.gz?3484" -O sakis3g.tar.gz

The extract the file

sudo tar -xzvf sakis3g.tar.gz

Make the extracted file executable

sudo chmod +x sakis3g

Before we can run the software we need to create a configuration file for it

sudo nano /etc/sakis3g.conf

Then add the following lines

CUSTOM_TTY="/dev/ttyAMA0"
BAUD=9600

Now we can load up the sakis3g software in interactive mode

sudo ./sakis3g --interactive

From there its just a simple case of:

Selecting "Connect 3G"

Select "Custom tty..." (this then uses the CUSTOM_TTY value from our config file, and also sets the correct baud rate)

Select the correct APN from the list or manully enter the details.

You should now be connected to the GSM network!