HOWTO: Receive SMS via 4G/LTE Huawei stick on Raspberry Pi 4 and forward them via Telegram

I live abroad and have only 1 sim card slot in my phone. It holds the SIM card of the country that I am in right now. But I also have another SIM card from my home country which receives my banking SMS codes. I can't afford to lose the "home" SIM card, so I decided to keep it in my house and forward the SMS messages to my main phone and computer via Telegram (just like Whatsapp, but so much better).

I also made a choice to use a 4G/LTE stick instead of 3G, because the 3G signal in my area is getting worse in worse due to operators upgrading their equipment.

Prerequisites

Raspberry Pi 4
Huawei E8372 (but can be any similar)

Step 1 - Get the Huawei card to work properly with Raspberry

Since I'm using a 4G/LTE Huawei card, there is an issue with it being originally booted in a "Hilux" mode which does not allow me to read incoming SMS messages.

To fix this, I need a special app call usb_modeswitch:

sudo apt update
sudo apt install usb_modeswitch

⚠️⚠️⚠️ usb_modeswitch -e should show you at least version 2.5.2. If it doesn't, something is wrong. Old versions of usb_modeswitch don't switch modes on this modem properly, so make sure that you have the latest version

Now you only need to set HuaweiAltModeGlobal=1 in /etc/usb_modeswitch.conf:

sudo sed -i "s/HuaweiAltModeGlobal=.*/HuaweiAltModeGlobal=1/" /etc/usb_modeswitch.conf

Now plug in the Huawei stick into the Raspberry, wait 10-15 seconds and the dmesg command should show you something like this:

[ 5053.514075] option 1-1.2:1.0: GSM modem (1-port) converter detected
[ 5053.514424] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB0
[ 5053.514962] option 1-1.2:1.1: GSM modem (1-port) converter detected
[ 5053.517558] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB2
[ 5053.518068] option 1-1.2:1.2: GSM modem (1-port) converter detected
[ 5053.518991] usb 1-1.2: GSM modem (1-port) converter now attached to ttyUSB3

If you don't see the ttyUSB0 above, then something is wrong. Do not proceed further.

If everything is OK, then you can add a udev rule which will attach the Huawei stick to /dev/sms. It is needed for the next step. Put the following code into /etc/udev/999-sms-gateway.rules:

SUBSYSTEM=="tty", ATTRS{idVendor}=="12d1", ATTRS{idProduct}=="155e", ENV{ID_USB_INTERFACE_NUM}=="00", SYMLINK+="sms", RUN+="/usr/bin/killall -SIGHUP gammu-smsd"

Important: 12d1 and 155e parts come from lsusb (Bus 001 Device 017: ID 12d1:155e Huawei Technologies Co., Ltd.). If you're using another card, then the 155e part might be different. So switch accordingly.

Unplug the Huawei card and plug it back in. After 10-15 seconds ls -l /dev/sms should start showing you this lrwxrwxrwx 1 root root 7 Apr 12 15:15 /dev/sms -> ttyUSB0 (or similar).

Step 2 - Receive SMS messages via Gammu

We will need a special program called Gammu. It will communicate with the Huawei stick and process the incoming SMS messages.

sudo apt install gammu

Put the following configuration into /etc/gammu-smsdrc:

# Configuration file for Gammu SMS Daemon

# Gammu library configuration, see gammurc(5)
[gammu]
port = /dev/sms
connection = at

# SMSD configuration, see gammu-smsdrc(5)
[smsd]
service = files
logfile = /var/log/gammu.log
CheckSecurity = 0
MultipartTimeout=20
# Increase for debugging information
debuglevel=0
HangupCalls=1

RunOnReceive=/gammu.sh

# Paths where messages are stored
inboxpath = /var/spool/gammu/inbox/
outboxpath = /var/spool/gammu/outbox/
sentsmspath = /var/spool/gammu/sent/
errorsmspath = /var/spool/gammu/error

Restart gammu with the new settings: sudo /etc/init.d/gammu-smsd restart Verify that gammu is working via: tail -f /var/log/gammu.log

Step 3 - forward SMS messages via Telegram

I won't go into the details of registering a bot via Telegram. It's pretty simple - send a message to @BotFather, register the robot and you will receive the authorization Token that you need to input into the script below.

Then you contact @get_id_bot to get your "Chat ID" (it's your hidden Telegram user id). Put it into the code below as well.

Send any message to your bot from your Telegram account. This will allow your bot to send you messages back (bots can't message random users first, this is done to fight spam).

Put the following text into /gammu.sh (this is what actually sends the message via Telegram):

#!/bin/bash

TOKEN="1733*****:AA****" # you get this from the @BotFather after creating your bot
CHAT_ID="9341******" # you get this from @get_id_bot

# no need to change anything below.

URL="https://api.telegram.org/bot${TOKEN}/sendMessage"

NL=$'\n'
declare -i i MSGS
MSGS=${SMS_MESSAGES}
CONTENT="${SMS_1_NUMBER}${NL}"
i=1
while [ $i -le $MSGS ]; do
    declare "PART"="SMS_${i}_TEXT"
    CONTENT="${CONTENT}${!PART}"
    i=$(($i+1))
done
CONTENT=${CONTENT//&/%26}
CONTENT=${CONTENT//</%3C}
CONTENT=${CONTENT//>/%3E}

eval "curl -s -X POST $URL -d chat_id=\"${CHAT_ID}\" -d text=\"${CONTENT}\""

Don't forget to chmod 755 /gammu.sh

Step 5 - restart Huawei stick without unplugging

I've noticed that sometimes my Huawei stick freezes and needs to be restarted. So I wrote a little script which restarts it every 15 minutes. Put it into /reset.sh:

#!/bin/bash
set -euo pipefail
IFS=$'\n\t'


datas=$(lsusb | grep -i hua | awk '/Bus/ {print $6}' | tr ":" "\n")
counter=0
for line in $datas
do
        counter=$((counter+1))
        if [ $counter = 1 ]
                then
                        VENDOR=$(echo "$line")
        fi

        if [ $counter = 2 ]
                then
                       PRODUCT=$(echo "$line")
        fi
done


for DIR in $(find /sys/bus/usb/devices/ -maxdepth 1 -type l); do
  if [[ -f $DIR/idVendor && -f $DIR/idProduct &&
        $(cat $DIR/idVendor) == $VENDOR && $(cat $DIR/idProduct) == $PRODUCT ]]; then
    echo found $DIR
    echo 0 > $DIR/authorized
    sleep 1.5
    echo 1 > $DIR/authorized
  fi
done

Don't forget to chmod 755 /reset.sh and add the following to sudo crontab -e -u root:

*/15 * * * * /reset.sh >/dev/null 2>&1

Links:

https://sms.ru/